* monitor (monitor_ptid): New global.

	* monitor (monitor_ptid): New global.
	(monitor_open): Silently add the main task to GDB's thread list.
	(monitor_close, monitor_mourn_inferior): Silently delete the main
	task from GDB's thread list.
	(monitor_thread_alive, monitor_pid_to_str): New.
	(init_base_monitor_ops): Register monitor_thread_alive and
	monitor_pid_to_str.
	(_initialize_remote_monitors): Initialize monitor_ptid.

	* gdbthread.h (delete_thread_silent): Declare.
	* thread.c (delete_thread): Rename to ...
	(delete_thread_1): ... this.  Add "silent" parameter.  If silent,
	don't do exit notifications.
	(delete_thread, delete_thread_silent): New, as wrappers to
	delete_thread_1.