Minor cleanup for redisplay interface and few related functions.

Minor cleanup for redisplay interface and few related functions.
* frame.h (enum text_cursor_kinds): Move from here...
* dispextern.h (enum text_cursor_kinds): ...to here.
(toplevel): Drop unnecessary declarations.
(struct redisplay_interface): Use bool and enum text_cursor_kinds
in update_window_end_hook and draw_window_cursor functions.
(display_and_set_cursor, x_update_cursor): Adjust prototypes.
* nsterm.m (ns_update_window_end, ns_draw_window_cursor):
* w32term.c (x_update_window_end,w32_draw_window_cursor):
* xterm.c (x_update_window_end, x_draw_window_cursor):
* xdisp.c (display_and_set_cursor, update_window_cursor)
(update_cursor_in_window_tree, x_update_cursor): Use bool and
enum text_cursor_kinds where appropriate.