rgw: recover from incomplete reshard attempt

rgw: recover from incomplete reshard attempt

In case a reshard attempt is left in an incomplete state, i.e., flags
still show resharding even though the bucket reshard lock isn't being
held, try to recover by taking the bucket reshard lock and clearing
flags associated with resharding.

This change requires access to an RGWBucketInfo object. So call stack
into this function should provide that to prevent unnecessary
work. Changes were made to provide this object.

Signed-off-by: J. Eric Ivancich <ivancich@redhat.com>