Include wx/colour.h according to precompiled headers of wx/wx.h (with other minor cleaning).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@39724 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/glcanvas.cpp

@@ -19,9 +19,9 @@
 #ifndef WX_PRECOMP
     #include "wx/app.h"
     #include "wx/frame.h"
+    #include "wx/colour.h"
 #endif // WX_PRECOMP
 
-#include "wx/colour.h"
 #include "wx/module.h"
 
 extern "C"