rename fNoListen to fListen and move to net

- better code readability and it belongs to net
- this is a prerequisite for a pull to add -listen to the GUI

src/net.cpp

@@ -45,6 +45,7 @@ static const int MAX_OUTBOUND_CONNECTIONS = 8;
 // Global state variables
 //
 bool fDiscover = true;
+bool fListen = true;
 uint64_t nLocalServices = NODE_NETWORK;
 CCriticalSection cs_mapLocalHost;
 map<CNetAddr, LocalServiceInfo> mapLocalHost;
@@ -96,7 +97,7 @@ unsigned short GetListenPort()
 // find 'best' local address for a particular peer
 bool GetLocal(CService& addr, const CNetAddr *paddrPeer)
 {
-    if (fNoListen)
+    if (!fListen)
         return false;
 
     int nBestScore = -1;