revert pp_formline -Wformat-nonliteral fix

Revert the part of 5d37acd6b65eb421e938a3fde62cc1edde467dae that was
intended to silence non-literal format warnings. It's giving compiler
errors on AIX due (I suspect) to overlong macro expansions.

The next commit will fix the warning in a more prosaic fashion
silence -Wformat-nonliteral in pp_formline