xfs: return committed status from xfs_trans_roll()

Some callers need to make error handling decisions based on whether
the current transaction successfully committed or not. Rename
xfs_trans_roll(), add a new parameter and provide a wrapper to
preserve existing callers.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>