cluster/dht: Unlink dst file after cleanup during migration

If a rename happens during migration, unlink fails. This leads
to stale xattrs, and Sticky bits still being set.

By removing the xattrs and Sticky bits from dst (through fd ops),
the stale link file would be cleaned up eventually (even if unlink
fails on src).

Change-Id: Iec537d021905438327a20e1d811aa06e74034364
BUG: 983399
Signed-off-by: shishir gowda <sgowda@redhat.com>
Reviewed-on: http://review.gluster.org/5316
Reviewed-by: Amar Tumballi <amarts@redhat.com>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>