freebsd: unbreak build after r16646

R=bmeurer@chromium.org

Review URL: https://codereview.chromium.org/85313002

Patch from Ben Noordhuis <ben@strongloop.com>.

git-svn-id: https://v8.googlecode.com/svn/branches/bleeding_edge@18035 ce2b1a6d-e550-0410-aec6-3dcde31c8c00