ports/184206: fix audio/x11amp build failure

[antoine at FreeBSD.org]

Synopsis: fix audio/x11amp build failure

Responsible-Changed-From-To: freebsd-ports-bugs->antoine
Responsible-Changed-By: antoine
Responsible-Changed-When: Mon Dec 2 19:19:23 UTC 2013
Responsible-Changed-Why: 
Take

http://www.freebsd.org/cgi/query-pr.cgi?pr=184206