* infrun.c (start_remote): Don't clear thread list here.

	* infrun.c (start_remote): Don't clear thread list here.
	* monitor.c (monitor_open): Include "gdbthread.h".  Clear thread
	list here.
	* remote.c (record_currthread): Upgrade the main thread and its
	entry in the thread list if this is the first time we hear about
	threads.
	(remote_thread_alive): Consider magic_null_ptid or a ptid without
	a tid member always alive.
	(remote_find_new_threads): Don't update the main thread here.
	(remote_start_remote): Clear thread list here.  Always add the
	main thread.
	(extended_remote_attach_1): Add the main thread here.
	(extended_remote_mourn_1): Re-add the main thread here.
	(extended_remote_create_inferior_1): Add a main thread.

	* Makefile.in (monitor.o): Depend on $(gdbthread_h).