Resolve build issues with macosx and xc32 1.32

* Changed VERSION define to use 'git rev-list HEAD --count'
to avoid issue on MacOSX where the result from wc is indented
and causes an invalid build command.

* Added define _SUPPRESS_PLIB_WARNING to remove warnings
about depricated headers being used.
Merge pull request #4 from antrorsum/fix/build_config_osx

Remove build issues with MacOSX and latest XC32 compiler [antrorsum]