[scudo] Lock FallbackTSD before draining it am: 76dac14491 Original change: https://googleplex-android-review.googlesource.com/c/platform/external/scudo/+/23184464 Change-Id: Ic9a39eb1692a36fec5ca5f3871bb8707d3f3f431 Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>