small net cleanup

- add comment for disabling sigpipe
- add closing comment in compat.h
- remove redundant check in net.h

src/net.h

@@ -356,12 +356,11 @@ public:
 
     ~CNode()
     {
-        if (hSocket != INVALID_SOCKET)
-        {
-            CloseSocket(hSocket);
-        }
+        CloseSocket(hSocket);
+
         if (pfilter)
             delete pfilter;
+
         GetNodeSignals().FinalizeNode(GetId());
     }