_ctypes_get_ffi_type never returns ffi_type_void. If the
return type is specified as None, we need set the libffi
return type to void, but just taking the output from
_ctypes_get_ffi_type will make the return type be sint.

This fixes two spots where ctypes accidentally converts
None return type to sint rather than void, causing crashes
on Emscripten targets.

ambv changed the title bpo-47197: Fix void return type handling in ctypes gh-91353: Fix void return type handling in ctypes

tiran changed the title gh-91353: Fix void return type handling in ctypes gh-91353: Fix void return type handling in ctypes (GH-32246)