Set the signal handler mask to empty to avoid valgrind warning
Set the signal handler mask to empty to avoid valgrind warning

Change-Id: I9c9fd12377b759aff38c7012edea74722dee9c1f
Reviewed-on: http://review.couchbase.org/37980
Reviewed-by: Chiyoung Seo <fcffc23db27b19ee4ebba46695ee6b50e09216a2@couchbase.com>
Tested-by: Michael Wiederhold <a17fed27eaa842282862ff7c1b9c8395a26ac320@couchbase.com>

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