Convert function definitions to standard C.

Convert function definitions to standard C.
* src/xterm.c (x_frame_of_widget, x_alloc_nearest_color_for_widget)
(x_alloc_lighter_color_for_widget, cvt_string_to_pixel)
(cvt_pixel_dtor, x_window_to_menu_bar, xt_action_hook)
(xaw_jump_callback, xaw_scroll_callback)
(x_create_toolkit_scroll_bar, x_set_toolkit_scroll_bar_thumb)
(x_wm_set_size_hint, x_activate_timeout_atimer): Convert
definitions to standard C.
* src/xmenu.c (menubar_id_to_frame, popup_get_selection)
(popup_activate_callback, popup_deactivate_callback)
(menu_highlight_callback, menubar_selection_callback)
(apply_systemfont_to_dialog, apply_systemfont_to_menu)
(free_frame_menubar, popup_selection_callback, as)
(create_and_show_popup_menu, dialog_selection_callback)
(create_and_show_dialog):
* src/xfns.c (hack_wm_protocols, x_window):
* src/xfaces.c (x_update_menu_appearance):
* src/widget.c (get_default_char_pixel_size, pixel_to_char_size)
(char_to_pixel_size, round_size_to_char, get_wm_shell)
(set_frame_size, update_wm_hints, setup_frame_gcs)
(update_various_frame_slots, update_from_various_frame_slots)
(EmacsFrameInitialize, EmacsFrameRealize, EmacsFrameResize)
(EmacsFrameSetValues, EmacsFrameQueryGeometry)
(EmacsFrameSetCharSize, widget_store_internal_border): Likewise.