[automerger skipped] Merge "Support learning the NAT64 prefix from two...

[automerger skipped] Merge "Support learning the NAT64 prefix from two different sources." into rvc-dev am: 4f7f6d67 -s ours am: af2c5375 -s ours am: 450d7154 -s ours am: 7d54b348 -s ours

am skip reason: Change-Id Ic7452431d2d9aea1ae59b67a9d8383c6cc5b3902 with SHA-1 e5b220d1 is in history

Change-Id: I4c8f97887bc902532b77e16871c5c0fa732e479c