guard shm alloc; rm OnWrite,dup lock in shm queue.

lichao

2021-04-30 3b93dc0dc34008cf25b2b12f6b026b3d9e4ed623

 src/shm.cpp

@@ -25,6 +25,7 @@
    mshm_t(open_or_create, name.c_str(), size, 0, AllowAll()),
    name_(name)
{
   pmutex_ = FindOrCreate<Mutex>("ShmSelfControlMutex0");
}

SharedMemory::~SharedMemory()