ports/178583: science/avogadro: Fix build with amd64

[edwin at FreeBSD.org]

Synopsis: science/avogadro: Fix build with amd64

Responsible-Changed-From-To: freebsd-ports-bugs->miwi
Responsible-Changed-By: edwin
Responsible-Changed-When: Mon May 13 18:11:17 UTC 2013
Responsible-Changed-Why: 
miwi@ wants this submitter's PRs (via the GNATS Auto Assign Tool)

http://www.freebsd.org/cgi/query-pr.cgi?pr=178583