MemcachedConnection: always close fd
MemcachedConnection: always close fd

Always close fd, even in SSL mode. SSL is just another layer on top of
the socket.

I was getting EMFILE after running lots of tests.

Change-Id: I07dda671a4ea3fed1605a38fcdd0dcef0eab5297
Reviewed-on: http://review.couchbase.org/72895
Reviewed-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@gmail.com>
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

daverigby/kv_engine,couchbase/memcached,daverigby/kv_engine,couchbase/memcached,couchbase/memcached,daverigby/kv_engine,couchbase/memcached,daverigby/kv_engine,daverigby/memcached,daverigby/memcached,daverigby/memcached,daverigby/memcached