docs/178073: [patch][porters-handbook]: add pkgconfig to USES, and drop USE_PKGCONFIG

[eadler at FreeBSD.org]

Synopsis: [patch][porters-handbook]: add pkgconfig to USES, and drop USE_PKGCONFIG

Responsible-Changed-From-To: freebsd-doc->eadler
Responsible-Changed-By: eadler
Responsible-Changed-When: Tue Apr 23 23:57:51 UTC 2013
Responsible-Changed-Why: 
I'll take it.

http://www.freebsd.org/cgi/query-pr.cgi?pr=178073