misc/57491: dhcpd segfaulting w/ RUNTIME_CHECK() timer-lock assertion

[bch@katy.localdomain]

>Number:         57491
>Category:       misc
>Synopsis:       dhcpd segfaulting w/ RUNTIME_CHECK() timer-lock assertion
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    misc-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Jun 28 22:10:00 +0000 2023
>Originator:     Bch
>Release:        NetBSD 10.99.4
>Organization:
	method logic digital
>Environment:
System: NetBSD katy 10.99.4 NetBSD 10.99.4 (GENERIC) #803: Wed Jun 28 10:46:09 PDT 2023 root@katy:/usr/obj/sys/arch/amd64/compile/GENERIC amd64
Architecture: x86_64
Machine: amd64
>Description:

/usr/src/external/mpl/bind/lib/libisc/../../dist/lib/isc/timer.c:223: fatal error: RUNTIME_CHECK(((__libc_mutex_lock(((&timer->lock))) == 0) ? 0 : 34) == 0) failed
[1]   Abort trap (core dumped) dhcpd -f -cf ./dhcpd.conf

>How-To-Repeat:
	I can trigger this immediately w/
        # dhcpd -f -cf ./dhcpd.conf

        ...and forcing a (Windows 11) client to attempt to renew its lease.
        Configuration is nothing special, nor new -- this (faulting) behaviour is a regression.
>Fix: