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/spinctrl.cpp

@@ -11,11 +11,13 @@
 // For compilers that support precompilation, includes "wx.h".
 #include "wx/wxprec.h"
 
-#include "wx/spinctrl.h"
-
 #if wxUSE_SPINCTRL
 
-#include "wx/utils.h"
+#include "wx/spinctrl.h"
+
+#ifndef WX_PRECOMP
+    #include "wx/utils.h"
+#endif
 
 #include "wx/textctrl.h"    // for wxEVT_COMMAND_TEXT_UPDATED
 #include "wx/math.h"