bind msgi to shm, change offset_ptr to abs offset.

lichao

2021-04-23 02ba913dc7bb5d711471b27f2ea23a897d0f2e28

 src/bh_api.cpp

@@ -10,6 +10,7 @@
{
TopicNode &ProcNode()
{
   static bool init_bind_msg_shm = MsgI::BindShm(BHomeShm());
   static TopicNode node(BHomeShm());
   return node;
}