Get rid of getFbSize()/getDesktopSize() in common

It was only used by WinVNC, so push it there instead.
diff --git a/win/winvnc/VNCServerWin32.cxx b/win/winvnc/VNCServerWin32.cxx
index d86384d..b164c65 100644
--- a/win/winvnc/VNCServerWin32.cxx
+++ b/win/winvnc/VNCServerWin32.cxx
@@ -63,7 +63,7 @@
       CreateEvent(0, FALSE, FALSE, "Global\\SessionEventTigerVNC") : 0),
     vncServer(CStr(ComputerName().buf), &desktop),
     thread_id(-1), runServer(false), isDesktopStarted(false),
-    httpServer(&vncServer), config(&sockMgr),
+    httpServer(this), config(&sockMgr),
     rfbSock(&sockMgr), httpSock(&sockMgr), trayIcon(0),
     queryConnectDialog(0)
 {