2fd63590ae
We removed the nonnull attributes from our headers long ago, but still __printflike() includes it implicitly. This will cause the NULL check to be optimized away in higher -O levels and it will also trigger a -Wnonnull-compare warning. Avoid warning with it in vwarnx(). Obtained from: DragonfLyBSD (git 6329e2f68af73662a1960240675e796ab586bcb1)