e2fsck: update the backup superblocks if the feature bitmasks are changed

If e2fsck adds or deletes any of the feature bitmasks, clear
EXT2_FLAG_MASTER_SB_ONLY so the backup superblocks are updated when
e2fsck finishes.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/e2fsck/unix.c b/e2fsck/unix.c
index 72545da..fbfd8e2 100644
--- a/e2fsck/unix.c
+++ b/e2fsck/unix.c
@@ -1252,6 +1252,7 @@
 			if (journal_size < 0) {
 				fs->super->s_feature_compat &=
 					~EXT3_FEATURE_COMPAT_HAS_JOURNAL;
+				fs->flags &= ~EXT2_FLAG_MASTER_SB_ONLY;
 				com_err(ctx->program_name, 0, 
 					_("Couldn't determine journal size"));
 				goto no_journal;