portable error(3)

["Jeremy C. Reed" <reed%reedmedia.net@localhost>]

glibc provides error(3)

http://www.gnu.org/software/libc/manual/html_node/Error-Messages.html
(see "The error function")

Does pkgsrc have a portable way of handling this?

I have looked at many packages and they have many different ways.

So I am wondering if we have an official way.

I noticed when upgrading tuxmath. It uses error() and it is not detected 
or defined if needed.

I looked at USE_FEATURES, but didn't see it as a choice.

  Jeremy C. Reed