Add prebuilt protobuf 3.9.1 to vendor partition. am: 112ddf05d3

Original change: https://android-review.googlesource.com/c/device/google/bramble/+/2297097

Change-Id: I6220b6964bb8125d3dd403a0bcc13e1ed6bf237c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>