remove length in ShmSocket ctor, not used.

lichao

2021-06-01 f7f8fbc85c48b003d1e3094a94a3528001977977

 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()