Merge branch 'wrap-gtk.h'

Add a wrapper for gtk/gtk.h allowing to avoid gcc 8 warnings when
including the GTK+ header directly.

See https://github.com/wxWidgets/wxWidgets/pull/814

include/wx/gtk/private.h

@@ -11,10 +11,9 @@
 #ifndef _WX_GTK_PRIVATE_H_
 #define _WX_GTK_PRIVATE_H_
 
-#include <gtk/gtk.h>
+#include "wx/gtk/private/wrapgtk.h"
 
 #include "wx/gtk/private/string.h"
-#include "wx/gtk/private/gtk2-compat.h"
 
 #ifndef G_VALUE_INIT
     // introduced in GLib 2.30

include/wx/gtk/private/addremovectrl.h

@@ -14,7 +14,7 @@
 #include "wx/bmpbuttn.h"
 #include "wx/toolbar.h"
 
-#include <gtk/gtk.h>
+#include "wx/gtk/private/wrapgtk.h"
 
 // ----------------------------------------------------------------------------
 // wxAddRemoveImpl

include/wx/gtk/private/gtk2-compat.h

@@ -539,6 +539,8 @@ static inline void wx_gtk_widget_get_preferred_size(GtkWidget* widget, GtkRequis
 }
 #define gtk_widget_get_preferred_size wx_gtk_widget_get_preferred_size
 
+#include <gdk/gdkkeysyms.h>
+
 #if defined(GDK_Alt_L) && !defined(GDK_KEY_Alt_L)
 #define GDK_KEY_Alt_L GDK_Alt_L
 #define GDK_KEY_Alt_R GDK_Alt_R

include/wx/gtk/private/wrapgtk.h

@@ -0,0 +1,19 @@
+///////////////////////////////////////////////////////////////////////////////
+// Name:        wx/gtk/private/wrapgtk.h
+// Purpose:     Include gtk/gtk.h without warnings and with compatibility
+// Author:      Vadim Zeitlin
+// Created:     2018-05-20
+// Copyright:   (c) 2018 Vadim Zeitlin <vadim@wxwidgets.org>
+// Licence:     wxWindows licence
+///////////////////////////////////////////////////////////////////////////////
+
+#ifndef _WX_GTK_PRIVATE_WRAPGTK_H_
+#define _WX_GTK_PRIVATE_WRAPGTK_H_
+
+wxGCC_WARNING_SUPPRESS(parentheses)
+#include <gtk/gtk.h>
+wxGCC_WARNING_RESTORE(parentheses)
+
+#include "wx/gtk/private/gtk2-compat.h"
+
+#endif // _WX_GTK_PRIVATE_WRAPGTK_H_

include/wx/nativewin.h

@@ -38,8 +38,6 @@
     typedef HWND wxNativeContainerWindowHandle;
     typedef HWND wxNativeWindowHandle;
 #elif defined(__WXGTK__)
-    #include <gtk/gtk.h>
-
     // GdkNativeWindow is guint32 under GDK/X11 and gpointer under GDK/WIN32
     #ifdef __UNIX__
         typedef unsigned long wxNativeContainerWindowId;