(kbd_buffer_gcpro): Renamed from

(kbd_buffer_gcpro): Renamed from
kbd_buffer_frame_or_window.  Now used for all Lisp objects
referenced from the input queue.
(kbd_buffer_store_event): Always use structure assignment for
copying input events.  Record all Lisp objects referenced from
events in kbd_buffer_gcpro.
(kbd_buffer_get_event): Construct Lisp `help-echo' events
differently from input events.  Test for prefix menu_bar_events
and TOOL_BAR_EVENTs differently.  Reset all slots used by an input
event in kbd_buffer_gcpro to nil.
(make_lispy_event) <TOOL_BAR_EVENT>: Treat an input event whose
frame_or_window is equal to its arg member as prefix events.
(stuff_buffered_input): Reset all slots in kbd_buffer_gcpro
used by an input event to nil.
(init_keyboard): Use two times the size of the input queue
for kbd_buffer_gcpro.
(syms_of_keyboard): Likewise.