Warn in headers that this is a fork. am: b5f6e0014e am: c2f9903179 am: 6090aa1e72

Original change: https://android-review.googlesource.com/c/platform/system/libhwbinder/+/1608701

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I682c73c40a3f705c63d97e5a3bc1b21a1ba7343b