ports/184876: games/xinvaders: Fix build with clang

[pawel at FreeBSD.org]

Synopsis: games/xinvaders: Fix build with clang

Responsible-Changed-From-To: freebsd-ports-bugs->pawel
Responsible-Changed-By: pawel
Responsible-Changed-When: Wed Dec 25 15:07:03 UTC 2013
Responsible-Changed-Why: 
I'll take it.

http://www.freebsd.org/cgi/query-pr.cgi?pr=184876