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

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@38972 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/scrolbar.cpp

@@ -14,7 +14,10 @@
 
 #include "wx/scrolbar.h"
 
-#include "wx/utils.h"
+#ifndef WX_PRECOMP
+    #include "wx/utils.h"
+#endif
+
 #include "wx/math.h"
 #include "wx/gtk/private.h"
 
@@ -344,4 +347,4 @@ wxScrollBar::GetClassDefaultAttributes(wxWindowVariant WXUNUSED(variant))
     return GetDefaultAttributesFromGTKWidget(gtk_vscrollbar_new);
 }
 
-#endif
+#endif // wxUSE_SCROLLBAR