use map instead of unordered to avoid newer libstdc++ dependency
use map instead of unordered to avoid newer libstdc++ dependency

using unordered_map caused a symbol dependency for:
_ZNKSt8__detail20_Prime_r@GLIBCXX_3.4.18

or similar for GLIBCXX_3.4.19, depending on exact g++ used.

jut-io/node-kafka-native,alfred-landrum/node-kafka-native,alfred-landrum/node-kafka-native,jut-io/node-kafka-native,alfred-landrum/node-kafka-native,jut-io/node-kafka-native,alfred-landrum/node-kafka-native,jut-io/node-kafka-native,jut-io/node-kafka-native,alfred-landrum/node-kafka-native