Upgrade spymemcached to 2.11.4

Change-Id: I9971faf5b9511f8764667654fc326469e0ad8d9c
Reviewed-on: http://review.couchbase.org/39006
Reviewed-by: Matt Ingenthron <matt@couchbase.com>
Tested-by: Michael Nitschinger <michael.nitschinger@couchbase.com>