Add library definition for test purposes am: 36058c1953

Original change: https://android-review.googlesource.com/c/platform/external/zopfli/+/2911566

Change-Id: I3202d6df77545c07d3964307f3be27e2d31b542b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>