Make C-x 5 o work on GNOME Shell-like Wayland compositors

Make C-x 5 o work on GNOME Shell-like Wayland compositors

* src/pgtkterm.c (pgtk_free_frame_resources)
(fill_background_by_face)
(pgtk_draw_glyphless_glyph_string_foreground)
(pgtk_draw_window_cursor): Fix coding style.
(pgtk_focus_frame): Use gtk_window_present_with_time whenever
possible.
(key_press_event): Set the last user time.
(pgtk_display_info_for_display): New function.
(key_release_event, construct_mouse_click, button_event): Set
the last user time.
(scroll_event, pgtk_parse_color, syms_of_pgtkterm)
(pgtk_begin_cr_clip): Fix coding style.
* src/pgtkterm.h (struct pgtk_output): New field
`last_user_time'.