Autorecord hook for powerdns auth 2.9.22

[anon]

This patch enables hooking of "fallback" lookup for reverse records by allowing users to define extra processing round for suffixes. with autoreverse-domains option user can define suffixes, that will be appended a .rev suffix, if no other backend gives any reply, and sent to another round of processing where a backend can claim them.

autoreverse-domains=8.e.6.0.1.0.0.2.ip6.arpa

gives us

f.e.e.b.d.a.e.d.f.e.e.b.d.a.e.d.0.0.0.0.0.0.5.0.8.e.6.0.1.0.0.2.ip6.arpa. 60 INPTR node-deadbeefdeadbeef.rev6e8-64.tdc.fi.

with approriate backend answering for f.e.e.b.d.a.e.d.f.e.e.b.d.a.e.d.0.0.0.0.0.0.5.0.8.e.6.0.1.0.0.2.ip6.arpa.rev IN ANY

[anon]

Autoreverse patch