Introduce cleanup to restore current_uiout

Introduce cleanup to restore current_uiout

Make a globally available cleanup from a pre-existing one in infrun.c.
This is used in a following patch.

gdb/ChangeLog:

	* infrun.c (restore_current_uiout_cleanup): Move to ui-out.c.
	(print_stop_event): Use make_cleanup_restore_current_uiout.
	* python/python.c (execute_gdb_command): Likewise.
	* ui-out.c (restore_current_uiout_cleanup): Move from infrun.c.
	(make_cleanup_restore_current_uiout): New function definition.
	* ui-out.h (make_cleanup_restore_current_uiout): New function
	declaration.
	* utils.c (do_restore_ui_out): Remove.
	(make_cleanup_restore_ui_out): Remove.
	* utils.h (make_cleanup_restore_ui_out): Remove.