ports/181624: Fix port: textproc/docbook-420 dependencies are incorrectly expressed

[crees at FreeBSD.org]

Synopsis: Fix port: textproc/docbook-420 dependencies are incorrectly expressed

Responsible-Changed-From-To: freebsd-ports-bugs->crees
Responsible-Changed-By: crees
Responsible-Changed-When: Wed Aug 28 17:41:30 UTC 2013
Responsible-Changed-Why: 
Mine.

http://www.freebsd.org/cgi/query-pr.cgi?pr=181624