sys/net/if_lagg_test:status_stress can lead to use-after-free in main (both before and after stable/14 was created), at least on aarch64

From: Mark Millard <marklmi_at_yahoo.com>
Date: Wed, 13 Sep 2023 07:02:18 UTC
See https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=273081#c5
and the backtrace in the prior comment.

The test context is aarch64.

Kyle Evans provided a kgdb patch for devel/gdb for aarch64 that
that finally let me track this down to the level of detail on
how to interpret the register values reported vs. what code
involved using the value.

I will say that I've not managed to produce the crash with
14.0-BETA1. But I have produced the crash in my personal
non-debug kernel builds and with the main snapshots dd'd to
media and booted and used.

===
Mark Millard
marklmi at yahoo.com