ext3: Don't update the superblock in ext3_statfs()

commit a71ce8c6 updated ext3_statfs()
to update the on-disk superblock counters, but modified this buffer
directly without any journaling of the change.  This is one of the
accesses that was causing the crc errors in journal replay as seen in
kernel.org bugzilla #14354.

The modifications were originally to keep the sb "more" in sync,
so that a readonly fsck of the device didn't flag this as an
error (as often), but apparently e2fsprogs deals with this differently
now, anyway.

Based on Ted's patch for ext4, which was in turn based on my
work on that bug and another preliminary patch...

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>