RESTRICT AUTOMERGE: Explicitly ignore the result of std::async am: c8512110f3

Original change: https://android-review.googlesource.com/c/platform/frameworks/native/+/2673908

Change-Id: I94744ece3427df579837b776af42de986edda698
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>