Merge pull request #7088 from rgacogne/rec-multi-protobuf

rec: Add support for more than one protobuf server

diff --cc pdns/pdns_recursor.cc
Simple merge

diff --cc pdns/rec-lua-conf.cc
Simple merge

diff --cc pdns/recursordist/test-syncres_cc.cc
Simple merge

diff --cc pdns/syncres.cc
Simple merge