resolv: Add classless reverse delegation tests for get{hostbyaddr,nameinfo}

The classless in-addr.arpa subnet delegation uses CNAME record for
reverse lookup addresses in the delegated subnetted range. Verify
the reverse delegation result for checking the CNAME record parsing
of the reverse DNS query.

Test: built, flashed, booted
      system/netd/tests/runtests.sh passes

Change-Id: I5d7a4a48d3c9acb1dfc8041d84cf5f0a91a610e7