Select sendrecv path based on collective data size (#391)

* Select sendrecv path based on collective data size

* Add comments on packing and unpacking group field

* Toggling RCCL_P2P_NET_DISABLE in combined calls unit tests

src/include/comm.h

@@ -74,7 +74,7 @@ struct ncclComm {
 
   void* bootstrap;
   // Bitmasks for ncclTransportP2pSetup
-  int connect;
+  int connect[NCCL_MAX_CONNS];
   uint32_t* connectSend;
   uint32_t* connectRecv;
 
@@ -128,7 +128,7 @@ struct ncclComm {
   volatile uint32_t *abortFlag;
 
   // Flags for enable P2P NET
-  uint32_t *p2pNet;
+  uint32_t p2pNet;
   uint32_t useIntraNet;
 
   // Device side of the communicator