put both versions of wxGetMousePosition in one place so they can use one implementation

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72983 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/utilsgtk.cpp

@@ -97,11 +97,6 @@ void wxDisplaySizeMM( int *width, int *height )
     if (height) *height = gdk_screen_height_mm();
 }
 
-void wxGetMousePosition( int* x, int* y )
-{
-    gdk_window_get_pointer(gtk_widget_get_root_window(wxGetRootWindow()), x, y, NULL);
-}
-
 bool wxColourDisplay()
 {
     return true;