chattr.1.in: Document the compression attribute flags E, X, and

chattr.1.in: Document the compression attribute flags E, X, and
	Z, and explain that chattr can't set or set these flags.
	(Addresses Debian Bug #151990)

fsetflags.c (fsetflags), fgetflags.c (fgetflags.c), setflags.c
	(setflags), getflags.c (getflags): Check to make sure the
	file is a regular file or a directory before attempting to
	use the ext2 ioctls.  Otherwise, return EOPNOTSUPP.
	(Addresses Debian Bug #152029).