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

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@38885 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/mgl/utils.cpp

@@ -1,5 +1,5 @@
 /////////////////////////////////////////////////////////////////////////////
-// Name:        utils.cpp
+// Name:        src/mgl/utils.cpp
 // Purpose:
 // Author:      Vaclav Slavik
 // Id:          $Id$
@@ -15,7 +15,10 @@
 #endif
 
 #include "wx/utils.h"
-#include "wx/string.h"
+
+#ifndef WX_PRECOMP
+    #include "wx/string.h"
+#endif
 
 #include "wx/intl.h"
 #include "wx/apptrait.h"