Support for internal modules was added in:

2db758c

As part of this, this line in tools/utils.py converts a path name into an identifier

   escaped_id = id.replace('/', '$')

Unfortunately support for a $ in an identifier is implementation specific and is not supported on AIX which causes compiler failures on the generated node_natives.h file.

I'd propose to change the line to:

  escaped_id = id.replace('/', '_')

@vkurchatkin comments ?