Also had to fix a few of the audacious files to get them to compile, mainly not using NULL in the input plugin constructor and casting the STREAMFILE functions (maybe some *nix compilers would've accepted those, but FreeBSD 12's Clang did not)
Needed to change how version.h was included to let it pick up the one from CMake's build location.
NOTE: Does not build with MinGW-w64 currently, does not have a way to build the audacious or XMPlay plugins.
Also add a getopt() implementation and a unistd.h from stackoverflow
to allow the existing code in test.c to build. (The normal unistd.h and
getopt() should still be used on systems that provide it. VC does not, so
that's why it's added.)
Also add a version.bat batch file that creates a VERSION.H file for VC
to include in the build. (Defines VERSION in the preprocessor, Batch file
pulls the version number from version.mk)
