> Inorder for /usr/src/usr.bin/xlint/lint1 code to link
> I must define YYDEBUG with a 'set YYDEBUG=1;export YYDEBUG' or
> I will get a link error that yydebug is undefined. 

> What is the proper way to fix this?

It's been fixed -- update your sources, rebuild and install yacc, and
then rebuild xlint.  

What happened is that we received a PR that suggested not defining the
external variable yydebug unless YYDEBUG was also defined.  It sounded
reasonable, so we put the change in.  Since then, we've discovered that
our own lint, plus a selection of third party programs, use yydebug 
without YYDEBUG.

	--jtc