Fix ICC warning about change of sign

debuggerstartparameters.h(86): warning #68: integer conversion resulted in a change of sign

-1 cannot be stored in a quint16. So change the port variable from
 quint16 to int.

Change-Id: I4c934624e7a315321088a6717bbc6e5e34083091
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>
Reviewed-by: hjk <hjk@theqtcompany.com>

src/plugins/debugger/debuggerstartparameters.h

@@ -74,7 +74,7 @@ public:
 
     // Used by Qml debugging.
     QString qmlServerAddress;
-    quint16 qmlServerPort = InvalidPort;
+    int qmlServerPort = InvalidPort;
 
     // Used by general remote debugging.
     QString remoteChannel;