Add GN build file for third_party hunspell library.

This way we can hook it up in the GN build on Chromium and it is
blocking chrome/renderer.

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

Review URL: https://codereview.chromium.org/348183002

git-svn-id: http://src.chromium.org/svn/trunk/deps/third_party/hunspell@278884 4ff67af0-8c30-449e-8e8b-ad334ec8d88c
1 file changed