[PATCH] Thread-safe libgfortran (PRs fortran/14943 and fortran/21647)

[David Edelsohn]

	We do not need anything that complicated.  gthr.h already includes
the appropriate AIX header.  We just need to remove _LARGE_FILES (with an
"S") and add _LARGE_FILE_API.

#ifdef _AIX
#undef _LARGE_FILES
#define _LARGE_FILE_API
#endif

That appears to work.

Thanks, David