Fix compilation without PCH after r73365.

Need to explicitly include wx/dialog.h to use wxDynamicCast to wxDialog.

See #14961.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73367 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/menu.cpp

@@ -17,6 +17,7 @@
 #ifndef WX_PRECOMP
     #include "wx/intl.h"
     #include "wx/log.h"
+    #include "wx/dialog.h"
     #include "wx/frame.h"
     #include "wx/bitmap.h"
     #include "wx/app.h"