net: wait until the node is destroyed to delete its recv buffer

when vRecvMsg becomes a private buffer, it won't make sense to allow other
threads to mess with it anymore.

src/net.cpp

@@ -437,11 +437,6 @@ void CNode::CloseSocketDisconnect()
         LogPrint("net", "disconnecting peer=%d\n", id);
         CloseSocket(hSocket);
     }
-
-    // in case this fails, we'll empty the recv buffer when the CNode is deleted
-    TRY_LOCK(cs_vRecvMsg, lockRecv);
-    if (lockRecv)
-        vRecvMsg.clear();
 }
 
 void CConnman::ClearBanned()