Merge pull request #4305 from rgacogne/dnsdist-lua-anon

dnsdist: Add an optional Lua callback for altering a Protobuf message

diff --cc pdns/README-dnsdist.md
Simple merge

diff --cc pdns/dnsdist-lua.cc
Simple merge

diff --cc pdns/dnsdist-lua2.cc
Simple merge

diff --cc pdns/dnsrulactions.hh
Simple merge

diff --cc pdns/iputils.hh
Simple merge

diff --cc pdns/protobuf.cc
Simple merge

diff --cc pdns/protobuf.hh
Simple merge