Add mariadb-client package (#255)

The mysqldump in mariadb-client is required by go-mysql-elasticsearch.

Author: honst

Dockerfile

@@ -6,6 +6,7 @@ RUN apk add --no-cache tini mariadb-client
 
 ADD . /go/src/github.com/siddontang/go-mysql-elasticsearch
 
+RUN apk add --no-cache mariadb-client
 RUN cd /go/src/github.com/siddontang/go-mysql-elasticsearch/ && \
     go build -o bin/go-mysql-elasticsearch ./cmd/go-mysql-elasticsearch && \
     cp -f ./bin/go-mysql-elasticsearch /go/bin/go-mysql-elasticsearch