rgw: prevent another leftover bucket index olh entry scenario

rgw: prevent another leftover bucket index olh entry scenario

If a call to bucket_index_link_olh or bucket_index_unlink_instance
fails, its associated pending xattr may have prevented the olh object
from being removed by another thread. We should do a best effort
cleanup attempt for this case by calling update_olh before returning
an error to the caller.

Signed-off-by: Cory Snyder <csnyder@1111systems.com>
(cherry picked from commit 570adec5bb8142f5baf1f05f0040e8afdb11ec05)

Conflicts:
	src/rgw/driver/rados/rgw_rados.cc

Cherry-pick notes:
- Conflicts due to rgw_rados file being moved into driver dir in later versions