Initialize callbacks in fuzzer am: 857ece4f am: 42b71bab am: e82f323e am: 4a6a388e am: f031a861

Original change: https://android-review.googlesource.com/c/platform/packages/modules/DnsResolver/+/2469762



Change-Id: I21737bca22cf353a66e3c61d41cbab401262d97d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>