gmod_src: Couple more file mac compat fixes

Revision 626
Couple more file mac compat fixesChanged Files:
[ul]
[li]trunk/src_garrysmod/garrysmod/FindIsDirectoryFix.h[/li][li]trunk/src_garrysmod/garrysmod/Library/gl_file.cpp[/li][/ul]
Committed By Garry Newman

trunk/src_garrysmod/garrysmod/FindIsDirectoryFix.h
Was this also affecting Linux servers?

Yeah, ages ago