sparse.c (ext2fs_list_backups, ext2fs_bg_has_super),

sparse.c (ext2fs_list_backups, ext2fs_bg_has_super),
	res_gdt.c (list_backups), closefs.c (ext2fs_bg_has_super),
	ext2fs.h: Move ext2fs_list_backups() to res_gdt.c, and
	ext2fs_bg_has_super() back to closefs.c.  There's no
	reason for the new file, since list_backups() isn't being
	used by any other functions, and can be made static, and
	all users of the ext2fs filesystem will have to call
	ext2fs_close() anyway.