[automerger skipped] Fix use-after-free in DNS64 discovery thread am:...

[automerger skipped] Fix use-after-free in DNS64 discovery thread am: 452f032d am: 5be90308 -s ours

am skip reason: Merged-In Id74ea4e6f54a00805d3cc8a9d7e15e58a473b7d3 with SHA-1 452f032d is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/packages/modules/DnsResolver/+/24372273



Change-Id: I96d669b81274f3d20974c10d7de17fb6da14dbf1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>