Add GN build file for third_party speex library.

This way we can hook it up in the GN build on Chromium.

BUG=None
TEST=gn gen out/Debug_gn && ninja -C out/Debug_gn speex
R=brettw@chromium.org

Review URL: https://codereview.chromium.org/299373002

git-svn-id: http://src.chromium.org/svn/trunk/deps/third_party/speex@272757 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
1 file changed