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

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@39745 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/textctrl.cpp

@@ -18,16 +18,15 @@
     #include "wx/utils.h"
     #include "wx/panel.h"
     #include "wx/settings.h"
+    #include "wx/math.h"
 #endif
 
-#include "wx/math.h"
 #include "wx/strconv.h"
 #include "wx/fontutil.h"        // for wxNativeFontInfo (GetNativeFontInfo())
 
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <ctype.h>
-#include "wx/math.h"
 
 #include "wx/gtk/private.h"
 #include <gdk/gdkkeysyms.h>