build: statically compile etcdctl binary

build

@@ -12,5 +12,5 @@ ln -s ${PWD} $GOPATH/src/${REPO_PATH}
 eval $(go env)
 
 go build -o bin/etcd ${REPO_PATH}
-go build -o bin/etcdctl ${REPO_PATH}/etcdctl
+CGO_ENABLED=0 go build -a -ldflags '-s' -o bin/etcdctl ${REPO_PATH}/etcdctl
 go build -o bin/etcd-migrate ${REPO_PATH}/migrate/cmd/etcd-migrate