Upgrade Spymemcached to 2.10.6

Change-Id: I48d1f2857f9d4b3e394e994f8a9344ace029a278
Reviewed-on: http://review.couchbase.org/33907
Reviewed-by: Michael Nitschinger <michael.nitschinger@couchbase.com>
Tested-by: Michael Nitschinger <michael.nitschinger@couchbase.com>