toolchain/56117: New test failures on amd64 since switch to gcc10

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

>Number:         56117
>Category:       toolchain
>Synopsis:       New test failures on amd64 since switch to gcc10
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    toolchain-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Apr 19 18:40:00 +0000 2021
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current, source date >= 2021.04.17.09.39.33
>Organization:
  
>Environment:
System: NetBSD
Architecture: x86_64
Machine: amd64
>Description:

There are some new ATF test failures on amd64:

  lib/libc/sys/t_ptrace_wait3:syscallemu1
  lib/libc/sys/t_ptrace_wait4:syscallemu1
  lib/libc/sys/t_ptrace_wait6:syscallemu1
  lib/libc/sys/t_ptrace_wait:syscallemu1
  lib/libc/sys/t_ptrace_waitpid:syscallemu1
  usr.bin/c++/t_call_once:call_once_pic_profile_32
  usr.bin/c++/t_cxxruntime:cxxruntime_pic_profile_32
  usr.bin/c++/t_hello:hello_pic_profile_32
  usr.bin/c++/t_pthread_once:pthread_once_pic_profile_32
  usr.bin/c++/t_static_destructor:static_destructor_pic_profile_32

since the recent period of build breakage during which the following
commits were made:

  2021.04.17.04.07.16 mrg src/external/gpl3/gcc/README.gcc10 1.11
  2021.04.17.04.07.16 mrg src/share/mk/bsd.own.mk 1.1240
  2021.04.17.04.08.32 mrg src/UPDATING 1.318
  2021.04.17.04.11.52 mrg src/doc/3RDPARTY 1.1795
  2021.04.17.04.11.52 mrg src/doc/CHANGES 1.2796
  2021.04.17.05.57.11 simonb src/common/lib/libc/string/memset2.c 1.6
  2021.04.17.06.02.35 simonb src/common/lib/libc/string/memset2.c 1.7
  2021.04.17.06.14.15 maya src/usr.bin/w/pr_time.c 1.19
  2021.04.17.06.14.15 maya src/usr.bin/w/w.c 1.91
  2021.04.17.08.06.58 simonb src/common/lib/libc/string/memset2.c 1.8
  2021.04.17.08.34.27 maya src/usr.bin/systat/ps.c 1.40
  2021.04.17.08.35.33 maya src/bin/ps/print.c 1.135
  2021.04.17.09.22.28 rin src/sys/arch/powerpc/include/oea/vmparam.h 1.21
  2021.04.17.09.39.33 mlelstv src/share/mk/bsd.own.mk 1.1241

I'm guessing the failures were triggered by the switch to gcc10.

>Fix: