librsync 2.3.1 fails to build under Windows no suitable type found TEST_BIG_ENDIAN

Building librsync 2.3.1 fails under Windows 10 where it used to work with librsync 2.2.1:

vagrant@WIN-2JV1T18KDCU C:\Users\vagrant\Develop\librsync-2.3.1>"C:\Program Files\CMake\bin\cmake.exe" -G "Visual Studio 15 2017" -A x64 -D BUILD_RDIFF=OFF . -D CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS=TRUE -D BUILD_SHARED_LIBS=TRUE -DCMAKE_INSTALL_PREFIX=C:/Users/vagrant/Develop/librsync.d
-- The C compiler identification is MSVC 19.16.27039.0 
-- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools/VC/Tools/MSVC/14.16.27
023/bin/Hostx86/x64/cl.exe
-- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools/VC/Tools/MSVC/14.16.27
023/bin/Hostx86/x64/cl.exe - works
-- Detecting C compiler ABI info 
-- Detecting C compiler ABI info - done 
-- Detecting C compile features 
-- Detecting C compile features - done
-- DO_RS_TRACE=0 
-- Looking for include file sys/file.h 
-- Looking for include file sys/file.h - not found 
-- Looking for include file sys/stat.h 
-- Looking for include file sys/stat.h - found 
-- Looking for include file sys/types.h 
-- Looking for include file sys/types.h - found 
-- Looking for include file unistd.h 
-- Looking for include file unistd.h - not found 
-- Looking for include file fcntl.h 
-- Looking for include file fcntl.h - found 
-- Looking for include file mcheck.h 
-- Looking for include file mcheck.h - not found 
-- Looking for include file zlib.h 
-- Looking for include file zlib.h - not found 
-- Looking for include file bzlib.h 
-- Looking for include file bzlib.h - not found 
-- Looking for __func__ 
-- Looking for __func__ - found
-- Looking for __FUNCTION__
-- Looking for __FUNCTION__ - found
-- Looking for fseeko
-- Looking for fseeko - not found
-- Looking for fseeko64
-- Looking for fseeko64 - not found
-- Looking for _fseeki64
-- Looking for _fseeki64 - found
-- Looking for fstat64
-- Looking for fstat64 - not found
-- Looking for _fstati64
-- Looking for _fstati64 - found
-- Looking for fileno
-- Looking for fileno - found
-- Looking for _fileno
-- Looking for _fileno - found
-- Looking for stdint.h
-- Looking for stdint.h - found
-- Looking for stddef.h
-- Looking for stddef.h - found
-- Check size of long
-- Check size of long - done
-- Check size of long long
-- Check size of long long - done
-- Check size of off_t
-- Check size of off_t - done
-- Check size of off64_t
-- Check size of off64_t - failed
-- Check size of size_t
-- Check size of size_t - done
-- Check size of unsigned int
-- Check size of unsigned int - done
-- Check size of unsigned long
-- Check size of unsigned long - done
-- Check size of unsigned short
-- Check size of unsigned short - done
-- Compiling to Win32 - printf "%zu" size_t formatting support disabled
-- Check if the system is big endian
-- Searching 16 bit integer
-- Check size of unsigned short
-- Check size of unsigned short - failed
-- Check size of unsigned int
-- Check size of unsigned int - failed
-- Check size of unsigned long
-- Check size of unsigned long - failed
CMake Error at C:/Program Files/CMake/share/cmake-3.17/Modules/TestBigEndian.cmake:50 (message):
  no suitable type found
Call Stack (most recent call first):
  CMakeLists.txt:115 (TEST_BIG_ENDIAN)


-- Configuring incomplete, errors occurred!
See also "C:/Users/vagrant/Develop/librsync-2.3.1/CMakeFiles/CMakeOutput.log".
See also "C:/Users/vagrant/Develop/librsync-2.3.1/CMakeFiles/CMakeError.log".

whereas on the exact same Windows with exactly the same command, it works with librsync 2.2.1:

vagrant@WIN-2JV1T18KDCU C:\Users\vagrant\Develop\librsync-2.2.1>"C:\Program Files\CMake\bin\cmake.exe" -G "Visual Stud
io 15 2017" -A x64 -D BUILD_RDIFF=OFF . -D CMAKE_WINDOWS_EXPORT_ALL_SYMBOLS=TRUE -D BUILD_SHARED_LIBS=TRUE -DCMAKE_INS
TALL_PREFIX=C:/Users/vagrant/Develop/librsync.d
-- The C compiler identification is MSVC 19.16.27039.0 
-- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools/VC/Tools/MSVC/14.16.27
023/bin/Hostx86/x64/cl.exe
-- Check for working C compiler: C:/Program Files (x86)/Microsoft Visual Studio/2017/BuildTools/VC/Tools/MSVC/14.16.27
023/bin/Hostx86/x64/cl.exe - works
-- Detecting C compiler ABI info 
-- Detecting C compiler ABI info - done 
-- Detecting C compile features 
-- Detecting C compile features - done
-- DO_RS_TRACE=0 
-- Looking for include file alloca.h
-- Looking for include file alloca.h - not found 
-- Looking for include file dlfcn.h 
-- Looking for include file dlfcn.h - not found 
-- Looking for include file inttypes.h 
-- Looking for include file inttypes.h - found 
-- Looking for include file memory.h 
-- Looking for include file memory.h - found 
-- Looking for include file stdint.h 
-- Looking for include file stdint.h - found 
-- Looking for include file stdlib.h 
-- Looking for include file stdlib.h - found 
-- Looking for include file strings.h 
-- Looking for include file strings.h - not found 
-- Looking for include file string.h 
-- Looking for include file string.h - found 
-- Looking for include file sys/stat.h 
-- Looking for include file sys/stat.h - found 
-- Looking for include file sys/types.h 
-- Looking for include file sys/types.h - found 
-- Looking for include file unistd.h 
-- Looking for include file unistd.h - not found 
-- Looking for include file bzlib.h 
-- Looking for include file bzlib.h - not found 
-- Looking for include file fcntl.h 
-- Looking for include file fcntl.h - found 
-- Looking for include file malloc.h 
-- Looking for include file malloc.h - found 
-- Looking for include file mcheck.h 
-- Looking for include file mcheck.h - not found 
-- Looking for include file sys/file.h 
-- Looking for include file sys/file.h - not found 
-- Looking for include file zlib.h 
-- Looking for include file zlib.h - not found 
-- Looking for alloca 
-- Looking for alloca - not found 
-- Looking for fseeko 
-- Looking for fseeko - not found 
-- Looking for fseeko64 
-- Looking for fseeko64 - not found 
-- Looking for _fseeki64 
-- Looking for _fseeki64 - found 
-- Looking for fstat64 
-- Looking for fstat64 - not found 
-- Looking for _fstati64 
-- Looking for _fstati64 - found 
-- Looking for fileno 
-- Looking for fileno - found 
-- Looking for _fileno 
-- Looking for _fileno - found 
-- Looking for memmove 
-- Looking for memmove - found 
-- Looking for memset 
-- Looking for memset - found
-- Looking for strchr
-- Looking for strchr - found
-- Looking for strerror
-- Looking for strerror - found
-- Looking for stddef.h
-- Looking for stddef.h - found
-- Check size of long
-- Check size of long - done
-- Check size of long long
-- Check size of long long - done
-- Check size of off_t
-- Check size of off_t - done
-- Check size of off64_t
-- Check size of off64_t - failed
-- Check size of size_t
-- Check size of size_t - done
-- Check size of unsigned int
-- Check size of unsigned int - done
-- Check size of unsigned long
-- Check size of unsigned long - done
-- Check size of unsigned short
-- Check size of unsigned short - done
-- Compiling to Win32 - printf "%zu" size_t formatting support disabled
-- Check if the system is big endian
-- Searching 16 bit integer
-- Check size of unsigned short
-- Check size of unsigned short - done
-- Searching 16 bit integer - Using unsigned short
-- Check if the system is big endian - little endian
-- System is little-endian.
-- PROJECT_NAME  = librsync
-- BUILD_HOSTNAME = WIN-2JV1T18KDCU
-- CMAKE_SYSTEM = Windows-10.0.17763
-- Could NOT find POPT (missing: POPT_LIBRARIES POPT_INCLUDE_DIRS)
-- Could NOT find BZip2 (missing: BZIP2_LIBRARIES BZIP2_INCLUDE_DIR)
-- Could NOT find ZLIB (missing: ZLIB_LIBRARY ZLIB_INCLUDE_DIR)
CMake Warning (dev) at C:/Program Files/CMake/share/cmake-3.17/Modules/FindPackageHandleStandardArgs.cmake:272 (messag
e):
  The package name passed to `find_package_handle_standard_args` (LIBB2) does
  not match the name of the calling package (libb2).  This can lead to
  problems in calling code that expects `find_package` result variables
  (e.g., `_FOUND`) to follow a certain pattern.
Call Stack (most recent call first):
  cmake/Findlibb2.cmake:12 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
  CMakeLists.txt:191 (find_package)
This warning is for project developers.  Use -Wno-dev to suppress it.

-- Could NOT find LIBB2 (missing: LIBB2_LIBRARIES LIBB2_INCLUDE_DIRS)
-- Using included blake2 implementation.
-- Could NOT find Doxygen (missing: DOXYGEN_EXECUTABLE)
-- CMAKE_C_FLAGS  = /DWIN32 /D_WINDOWS /W3
-- Configuring done
-- Generating done
-- Build files have been written to: C:/Users/vagrant/Develop/librsync-2.2.1

I attach the log files for both runs:
CMakeError_221.log
CMakeError_231.log
CMakeOutput_221.log
CMakeOutput_231.log

The results are consistent within Travis CI and in my Vagrant/Ansible generated VM: rdiff-backup/rdiff-backup@a28f521 (Travis got a new Python version but it is unrelated, the VM was already on 3.7.7).

Any help is much appreciated.