added missing mutex lock.

git-svn-id: http://svn.code.sf.net/p/retroshare/code/branches/v0.5-gxs_finale@6885 b45a01b8-16f6-495d-af2f-9b41ad6348cc

libretroshare/src/services/p3idservice.cc

@@ -1368,6 +1368,8 @@ bool p3IdService::cache_start_load()
 		GxsTokenQueue::queueRequest(token, GXSIDREQ_CACHELOAD);	
 		std::set<RsGxsGroupId> groupIdSet;
 		groupIdSet.insert(groupIds.begin(), groupIds.end());
+
+		RsStackMutex stack(mIdMtx); /********** STACK LOCKED MTX ******/
 		mGroupsToCache.insert(std::make_pair(token, groupIdSet));
 	}
 	return 1;