Preserve tty top-frames under various window-changing operations.

Preserve tty top-frames under various window-changing operations.

* subr.el (with-selected-window): Preserve the selected window's
terminal's top-frame.

* window.el (save-selected-window): Likewise.

* frame.c (delete_frame): When selecting a frame on a different
text terminal, do not alter the terminal's top-frame.

* term.c (Ftty_top_frame): New function.

* xdisp.c (format_mode_line_unwind_data): Record the target
frame's selected window and its terminal's top-frame.
(unwind_format_mode_line): Restore them.
(x_consider_frame_title, display_mode_line, Fformat_mode_line):
Callers changed.
(x_consider_frame_title): Do not condition on HAVE_WINDOW_SYSTEM,
since tty frames can be explicitly named.
(prepare_menu_bars): Likewise.