Make gyp work on OpenBSD.

BUG=none

Patch by Pawel Hajdan <phajdan.jr@chromium.org>
Review URL: https://codereview.chromium.org/11768002

git-svn-id: http://gyp.googlecode.com/svn/trunk@1592 78cadc50-ecff-11dd-a971-7dbc132099af