Merge pull request #5576 from rgacogne/dnsdist-sharded-mmsg

dnsdist: Cache sharding, recvmmsg and CPU pinning support

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

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

diff --cc pdns/dnsdistdist/dnsrulactions.cc
Simple merge

diff --cc pdns/dnsdistdist/docs/reference/config.rst
Simple merge

diff --cc pdns/dnsrulactions.hh
Simple merge