Writing portfiels: How to avoid hardcoded paths?

[Giorgio Valoti]

Hi all, with the help of William Siegrist I wrote a portfile for  
pgpool-II (ticket #14647). I’ve added the following environment setting:
configure.env           PATH=$env(PATH):${prefix}/lib/postgresql83/bin

In order to make pg_config available at configure time. Is there a  
way to avoid hard coding the path?

Thank you in advance.
--
Giorgio Valoti