* xterm.h: Rename x_non_menubar_window_to_frame to

* xterm.h: Rename x_non_menubar_window_to_frame to
x_menubar_window_to_frame

* xterm.c: Remove declarations also in xterm.h
(XTmouse_position): Do not return valid positions
for clicks in the menubar and the toolbar for Gtk+.

* xfns.c (x_any_window_to_frame): Assume less about Gtk+ internals,
if the widget for the event has the same top level as a frame,
return the frame.
(x_menubar_window_to_frame): Detect menu bar even with Gtk+
internal windows, bug #4122.
(x_non_menubar_window_to_frame): Remove.