(x_autoselect_window_p): Remove variable.

(x_autoselect_window_p): Remove variable.
(last_window): New variable.
(XTreassert_line_highlight, x_change_line_highlight): Remove
declarations.
(mac_focus_changed, x_detect_focus_change): New functions and
declarations.
(XTextExtents16, front_emacs_window): Remove function.
(mac_focus_frame): New function.
(XTmouse_position, do_menu_choice, do_zoom_window, XTread_socket)
(mac_check_for_quit_char): Use it instead of front_emacs_window.
(x_scroll_bar_report_motion): Obtain window from control owner.
(x_make_frame_invisible): Set window manager size hint.
(do_mouse_moved): Remove function.
(XTread_socket): Move its contents here.  Generate select-window
event on mouse movement if needed.  Use x_detect_focus_change on
activate/deactivate events.  Don't deiconify frame or invalidate
window rectangle when dnd items are dropped.  Don't
activate/deactivate root control.
(frame_highlight, frame_unhighlight): Activate/deactivate root
control here.
(syms_of_macterm): Delete DEFVAR_BOOL for x_autoselect_window_p.