fstests: filter readonly mount error messages

util-linux commit 6dede2f2f7c5 ("libmount: support MS_RDONLY on
write-protected devices") changed the error message on read-only
block device, and in the failure case printed one line message
instead of two (for details please see comments in common/filter),
and this change broke generic/050 and overlay/035.

Fix it by adding more filter rules to _filter_ro_mount and updating
associated .out files to unify the output from both old and new
util-linux versions.

Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>

tests/overlay/035

@@ -69,7 +69,7 @@ mkdir -p $lowerdir1 $lowerdir2 $upperdir $workdir
 $MOUNT_PROG -t overlay -o"lowerdir=$lowerdir2:$lowerdir1" \
 			$OVL_BASE_SCRATCH_MNT $SCRATCH_MNT
 touch $SCRATCH_MNT/foo 2>&1 | _filter_scratch
-_scratch_remount rw 2>&1 | _filter_scratch
+_scratch_remount rw 2>&1 | _filter_ro_mount
 $UMOUNT_PROG $SCRATCH_MNT
 
 # Make workdir immutable to prevent workdir re-create on mount
@@ -79,7 +79,7 @@ $CHATTR_PROG +i $workdir
 # Verify that overlay is mounted read-only and that it cannot be remounted rw.
 _overlay_scratch_mount_dirs $lowerdir2 $upperdir $workdir
 touch $SCRATCH_MNT/bar 2>&1 | _filter_scratch
-_scratch_remount rw 2>&1 | _filter_scratch
+_scratch_remount rw 2>&1 | _filter_ro_mount
 
 # success, all done
 status=0

tests/overlay/035.out

@@ -1,5 +1,5 @@
 QA output created by 035
 touch: cannot touch 'SCRATCH_MNT/foo': Read-only file system
-mount: cannot remount SCRATCH_DEV read-write, is write-protected
+mount: cannot remount device read-write, is write-protected
 touch: cannot touch 'SCRATCH_MNT/bar': Read-only file system
-mount: cannot remount SCRATCH_DEV read-write, is write-protected
+mount: cannot remount device read-write, is write-protected