adaint.c (w32_epoch_offset): Define static const at file level.

adaint.c (w32_epoch_offset): Define static const at file level.

	* ada/adaint.c (w32_epoch_offset): Define static const at file
	level.
	(win32_filetime): Replace offset with w32_epoch_offset. Use NULL
	rather than t_create, t_access in call to GetFileTime. Use union
	to convert between FILETIME and  unsigned long long.
	(__gnat_file_time_name): Test for invalid file handle.
	(__gnat_set_filetime_name): Support win32 targets using
	w32api SetFileTime.

From-SVN: r72840