cffi: add upstream PKG_CONFIG fix

BUG=chromium:985180
TEST=CQ passes

Change-Id: Ia53b13752766e3ed157f68eb556b4441e8d3d6cb
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/overlays/portage-stable/+/2213180
Reviewed-by: Chris McDonald <cjmcdonald@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>
Commit-Queue: Mike Frysinger <vapier@chromium.org>
1 file changed