* corelow.c (add_to_thread_list): If this is the first time we

	* corelow.c (add_to_thread_list): If this is the first time we
	hear about thread info, update inferior_ptid.
	(core_open): Clear the thread list and set inferior_ptid before
	acknowledging a new inferior.  Find threads before fetching
	register info.  Give an upper target layer a chance to find and
	claim new threads.  Print core generation and stop signal info
	after finding new threads.
	(get_core_register_section): Look at the lwp member of
	inferior_ptid for detecting if we have threads info, instead of
	the pid member.
	(core_pid_to_str): New.
	(init_core_ops): Register core_pid_to_str.