* defs.h (deprecated_registers_changed_hook): Delete declaration.

	* defs.h (deprecated_registers_changed_hook): Delete declaration.
	* interps.c (clear_interpreter_hooks): Do not clear
	deprecated_registers_changed_hook.
	* regcache.c (registers_changed): Do not call it.
	* top.c (deprecated_registers_changed_hook): Do not define it.
	* mi/mi-interp.c (mi_command_loop): Do not clear it.
	* tui/tui-hooks.c (tui_install_hooks): Do not install it.
	(tui_remove_hooks): Do not remove it.
	(tui_selected_frame_level_changed_hook): Check for negative level.
	Use get_selected_frame.
	(tui_registers_changed_hook): Deleted.