Use #pragma once header guard. am: 0cd3943fb8 am: a9b336ef84 am: b2c0842e51 Original change: https://android-review.googlesource.com/c/platform/system/unwinding/+/2070169 Change-Id: I7631d60d2ca6e0dd2d6dedb1c4ae8efb8b1ad19f Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>