lib/53343: t_ptrace_wait*:traceme_vfork_crash_bus test cases fail

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         53343
>Category:       lib
>Synopsis:       t_ptrace_wait*:traceme_vfork_crash_bus test cases fail
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jun 05 14:50:00 +0000 2018
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current, source date >= 2018.05.30.17.48.13
>Organization:
>Environment:
System: NetBSD
Architecture: x86_64
Machine: amd64
>Description:

The following test cases are failing:

  lib/libc/sys/t_ptrace_waitpid/traceme_vfork_crash_bus
  lib/libc/sys/t_ptrace_wait6/traceme_vfork_crash_bus
  lib/libc/sys/t_ptrace_wait3/traceme_vfork_crash_bus
  lib/libc/sys/t_ptrace_wait4/traceme_vfork_crash_bus
  lib/libc/sys/t_ptrace_wait/traceme_vfork_crash_bus

since the following commits:

  2018.05.30.17.31.34 kamil src/tests/kernel/h_segv.c 1.6
  2018.05.30.17.31.34 kamil src/tests/lib/libc/sys/t_ptrace_wait.h 1.10
  2018.05.30.17.48.13 kamil src/tests/kernel/h_segv.c 1.7
  2018.05.30.17.48.13 kamil src/tests/lib/libc/sys/t_ptrace_wait.h 1.11

on multiple platforms (at least amd64, i386 and sparc), on both
qemu and real hardawre.  Logs at (for example)

  http://www.gson.org/netbsd/bugs/build/amd64-baremetal/commits-2018.05.html#2018.05.30.17.48.13

>How-To-Repeat:

Inspect test logs.

>Fix: