ANDROID: Delete Android.mk to avoid conflicts with other imports. am: c5427947e7 am: ff579d2ec5 am: 95839a5b03

Original change: https://android-review.googlesource.com/c/platform/external/libwebm/+/1504155

Change-Id: I4741fc2f95eec460ea626cf04bb28cb19ef5645b