port-sparc64/54810: sparc64 pool_redzone_check errors during install

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

>Number:         54810
>Category:       port-sparc64
>Synopsis:       sparc64 pool_redzone_check errors during install
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    port-sparc64-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Dec 30 08:15:00 +0000 2019
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current
>Organization:

>Environment:
System: NetBSD
Architecture: sparc64
Machine: sparc64
>Description:

The sparc64 port is printing messages like

  pool_redzone_check: 0x125760c20: 0x00 != 0x66

during the set extraction phase of the install.  On the TNF testbed,
they appeared some time between source dates 2019.11.16.04.10.33 and
2019.11.28.14.21.25, but were only warnings until they were changed
into a panic in

  2019.12.27.15.49.20 maxv src/sys/kern/subr_pool.c 1.264

Log output from the latest such panic is at

  http://releng.netbsd.org/b5reports/sparc64/2019/2019.12.29.09.17.51/install.log

>How-To-Repeat:

Using versions of qemu and glib2 that don't suffer from PR 54310, e.g.,
qemu-4.1.0nb2 with glib2-2.60.6.

>Fix: