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/util.cpp

@@ -94,7 +94,6 @@ bool fPrintToDebugLog = true;
 bool fDaemon = false;
 bool fServer = false;
 string strMiscWarning;
-bool fNoListen = false;
 bool fLogTimestamps = false;
 volatile bool fReopenDebugLog = false;
 CClientUIInterface uiInterface;