same-inode.h: don't depend on _GL_WINDOWS_STAT_INODES

It looks like assuming _GL_WINDOWS_STAT_INODES is 1 is likely our best
option.  See gnulib/m4/windows-stat-inodes.m4.  Note that this doesn't
really make SAME_INODE usable on windows hosts as a number of the
likely filesystems (FAT, HPFS, or NTFS) don't support st_ino.

	* same-inode.h (SAME_INODE <_WIN32>): Remove _GL_WINDOWS_STAT_INODES
	test.  Assume it is true.