ssh_dispatch_run_fatal on Rpi4 building www/firefox

[bob prohaska]

While attempting to compile www/firefox on an RPi4 running -current
the make process stopped with 

Bad packet length 3554809687.
ssh_dispatch_run_fatal: Connection to 192.168.1.11 port 22: Connection corrupted

on the controlling terminal.

After updating to 14.0-CURRENT FreeBSD 14.0-CURRENT #15 main-8cca7b7f2: 
Tue Apr 13 17:46:39 PDT 2021

the error promptly recurred if make was restarted without cleaning. 

As an experiment, I've restarted the make process via a serial connection
and it didn't immediately reproduce the error. In all cases the make 
command is

make -DBATCH MAKE_JOBS_UNSAFE=yes MAKE_JOBS_NUMBER=4 DISABLE_VULNERABILITIES=yes > make.log

and is run in the background. The same make command successfully compiled
www/chromium via ssh, so I don't think the culprit's the command line.  

I rather doubt this is a www/firefox problem, but include freebsd-ports
in hopes somebody might recognize the error.

Make generates a torrent of warnings using the serial connection, such as:

#if IN_HEADER(__GTK_ITEM_FACTORY_H__)
    ^
./gtkalias.h:10:19: note: expanded from macro 'IN_HEADER'
#define IN_HEADER defined
                  ^
./gtkalias.h:5366:5: warning: macro expansion producing 'defined' has undefined behavior [-Wexpansion-to-defined]
#if IN_HEADER(__GTK_LABEL_H__)
    ^
./gtkalias.h:10:19: note: expanded from macro 'IN_HEADER'
#define IN_HEADER defined
                  ^
but seems to keep running via the serial connection. Top reports that
cc is in state TTYOUT, with WCPU no higher than a few percent, running
only one thread.

Thanks for reading, and any ideas.

bob prohaska