Adjust fork/vfork/exec to pass ptids around.

	Adjust fork/vfork/exec to pass ptids around.

	* target.h (struct target_waitstatus): Store related_pid as a ptid.
	(inferior_has_forked, inferior_has_vforked, inferior_has_execd):
	Take a ptid_t.
	* breakpoint.h (struct breakpoint): Change forked_inferior_pid
	type to ptid.
	* breakpoint.c (print_it_typical, bpstat_check_location)
	(print_one_breakpoint_location, set_raw_breakpoint_without_location)
	(create_fork_vfork_event_catchpoint): Adjust.
	* infrun.c (fork_event): Change parent_pid and child_pid types to
	ptid.
	(follow_exec, inferior_has_forked, inferior_has_vforked)
	(inferior_has_execd): Take a ptid_t and don't trim it.
	* linux-thread-db.c (thread_db_wait): Don't trim the returned ptid.
	* linux-nat.c (linux_child_follow_fork): Adjust.
	* inf-ptrace.c (inf_ptrace_wait): Adjust.
	* inf-ttrace.c (inf_ttrace_wait): Adjust.
	* win32-nat.c (get_win32_debug_event): Don't set related_pid.