Fix menu bar activation with click for Motif/Lesstif.

Fix menu bar activation with click for Motif/Lesstif.

* src/xdisp.c (pending_menu_activation): Remove extern declaration.
(prepare_menu_bars): Remove setting of pending_menu_activation.

* src/xmenu.c (pending_menu_activation): Remove.
(x_activate_menubar): Set popup_activated_flag for Xt also. Remove
setting of pending_menu_activation.
(set_frame_menubar): Remove check of pending_menu_activation.
Declare menubar_size before code.  Correct spelling in comment.

* src/xterm.c (xm_scroll_callback, x_process_timeouts): K&R => prototype.
(SET_SAVED_KEY_EVENT): Remove (not used).
(SET_SAVED_MENU_EVENT): Rename to SET_SAVED_BUTTON_EVENT and
remove size parameter.
(handle_one_xevent): Check popup_activated () for menu for Xt also.
Remove #ifdef USE_GTK around finish = X_EVENT_DROP.
Remove #ifdef USE_MOTIF code that did SET_SAVED_BUTTON_EVENT for
ButtonRelease.