Add the new TAP connection flag for a registered TAP client.
Add the new TAP connection flag for a registered TAP client.

This change adds the new TAP connection flag to support the
registered TAP client (e.g., incremental backup client).

daverigby/kv_engine,mrkwse/memcached,zbase/memcached,cloudrain21/memcached-1,Metaswitch/memcached,daverigby/memcached,mrkwse/memcached,zbase/memcached,owendCB/memcached,Metaswitch/memcached,jimwwalker/memcached,mrkwse/memcached,jimwwalker/memcached,jimwwalker/memcached,Metaswitch/memcached,couchbase/memcached,abhinavdangeti/memcached,owendCB/memcached,couchbase/memcached,daverigby/memcached,abhinavdangeti/memcached,abhinavdangeti/memcached,cloudrain21/memcached-1,cloudrain21/memcached-1,zbase/memcached,daverigby/kv_engine,mrkwse/memcached,Metaswitch/memcached,abhinavdangeti/memcached,zbase/memcached,daverigby/kv_engine,owendCB/memcached,daverigby/kv_engine,zbase/memcached,Metaswitch/memcached,abhinavdangeti/memcached,daverigby/memcached,owendCB/memcached,daverigby/memcached,couchbase/memcached,couchbase/memcached,cloudrain21/memcached-1