I installed the latest getdns with Homebew and compilation fails because a constant cannot be found:
CXX(target) Release/obj.target/getdns/src/GNConstants.o
../src/GNConstants.cpp:87:53: error: use of undeclared identifier 'GETDNS_APPEND_NAME_TO_SINGLE_LABEL_FIRST'
SetConstant("APPEND_NAME_TO_SINGLE_LABEL_FIRST",GETDNS_APPEND_NAME_TO_SINGLE_LABEL_FIRST,exports);
^