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

[automerger skipped] Fix use-after-free in DNS64 discovery thread am: 452f032d am: d81ab119 am: 13a28785 am: 29fde604 -s ours am: c58ad27c -s ours am: f322f5e0 -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: I49389ca32e3eb40801135dee87c3d32aaffaced6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>