[automerger skipped] Add AudioFlinger to Thread thread safety annotations am: f8635b65 -s ours

am skip reason: Merged-In I9b4573be8f5f6546d6979f69a9ad8d19e5d95bc6 with SHA-1 972bec1c is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/24819852



Change-Id: I099701864e611ef3972211366357d8ef6f0c9d18
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>