Always use UTF-8 for GTK+ strings.

Strings returned and accepted by GTK+ functions always use UTF-8 independently
of the current locale and of the file name encoding we use. So use UTF-8
instead of wxConvFileName everywhere where we deal with GTK+ directly.

Closes #11743.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@63549 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/gtk/dirdlg.cpp

@@ -172,7 +172,7 @@ void wxDirDialog::SetPath(const wxString& dir)
 wxString wxDirDialog::GetPath() const
 {
     wxGtkString str(gtk_file_chooser_get_filename(GTK_FILE_CHOOSER(m_widget)));
-    return wxString(str, *wxConvFileName);
+    return wxString::FromUTF8(str);
 }
 
 #endif // wxUSE_DIRDLG