/usr/src/sys/net/if_epair.c:181:6: error: ...

From: bob prohaska <fbsd_at_www.zefox.net>
Date: Wed, 23 Mar 2022 01:26:57 UTC 
A Pi2 running 
FreeBSD www.zefox.net 12.3-STABLE FreeBSD 12.3-STABLE r371495 GENERIC  arm

stops buildkernel with:
--- if_epair.o ---
/usr/src/sys/net/if_epair.c:181:6: error: implicit declaration of function 'atomic_testandclear_long' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
        if (atomic_testandclear_long(&q->state, BIT_MBUF_QUEUED))
            ^

Not sure if this is specific to the Raspberry Pi 2, it didn't show up on a pair of Pi3's
and a single Pi4. The system is still using svnlite, info reports
root@www:/usr/src # svnlite info
Path: .
Working Copy Root Path: /usr/src
URL: svn://svn.freebsd.org/base/stable/12
Relative URL: ^/stable/12
Repository Root: svn://svn.freebsd.org/base
Repository UUID: ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Revision: 371771
Node Kind: directory
Schedule: normal
Last Changed Author: 0mp
Last Changed Rev: 371771
Last Changed Date: 2022-03-22 15:28:40 -0700 (Tue, 22 Mar 2022)
 

Didn't see anything similar on bugs.freebsd.org, if it's worth a bug report or
there's a workaround please post. It was built using WITH_META_MODE if that 
matters. 

Thanks for reading,

bob prohaska