xfs_repair: only update in-core extent state after scanning full extent

xfs_repair: only update in-core extent state after scanning full extent

In process_bmbt_reclist_int, only update the in-core extent state after
clearing the entire extent for conflicts.  If we encounter conflicts
we'll try rebuilding the fork from rmap data and rescanning the fork.
It is essential to avoid polluting the in-memory state with garbage
data so that we don't end up nuking other files needlessly.  Found by
fuzzing recs[1].blockcount = middlebit in xfs/380.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>