安装confluent-kafka-go出错时，请使用brew安装pkg-config，手动go get安装的pkg-config还不行。。。
错误提示：
go get -u github.com/confluentinc/confluent-kafka-go/kafka # pkg-config --cflags -- rdkafka error $GOPATH: no library found in $GOPATH: rdkafka error github.com: PKG_CONDIF_GITHUB not exported, skipping github.com lookup error $PKG_CONFIG_PATH: open rdkafka.pc: no such file or directory error <autogenerated>: no library found in $GOPATH: rdkafka pkg-config: exit status 1
解决：
brew install pkg-config
error $GOPATH: no library found in $GOPATH: rdkafka
原文：https://www.cnblogs.com/highend/p/fix_rdkafka_library_not_found.html