contrib: Dockerfile: reformat, and use --no-install-recommends

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

contrib/Dockerfile.test

@@ -10,24 +10,42 @@ ARG GOLANG_VERSION=1.11
 
 # Install proto3
 FROM golang:${GOLANG_VERSION} AS proto3
-RUN apt-get update && apt-get install -y autoconf automake g++ libtool unzip
+RUN apt-get update && apt-get install -y \
+   autoconf \
+   automake \
+   g++ \
+   libtool \
+   unzip \
+ --no-install-recommends
+
 COPY script/setup/install-protobuf install-protobuf
 RUN ./install-protobuf
 
 # Install runc
 FROM golang:${GOLANG_VERSION} AS runc
-RUN apt-get update && apt-get install -y curl libseccomp-dev
+RUN apt-get update && apt-get install -y \
+    curl \
+    libseccomp-dev \
+  --no-install-recommends
+
 COPY vendor.conf /go/src/github.com/containerd/containerd/vendor.conf
 COPY script/setup/install-runc install-runc
 RUN ./install-runc
 
 FROM golang:${GOLANG_VERSION} AS dev
-RUN apt-get update && apt-get install -y btrfs-tools gcc git libseccomp-dev make xfsprogs
+RUN apt-get update && apt-get install -y \
+    btrfs-tools \
+    gcc \
+    git \
+    libseccomp-dev \
+    make \
+    xfsprogs \
+  --no-install-recommends
 
-COPY --from=proto3 /usr/local/bin/protoc /usr/local/bin/protoc
+COPY --from=proto3 /usr/local/bin/protoc     /usr/local/bin/protoc
 COPY --from=proto3 /usr/local/include/google /usr/local/include/google
+COPY --from=runc   /usr/local/sbin/runc      /usr/local/go/bin/runc
 
-COPY --from=runc /usr/local/sbin/runc /usr/local/go/bin/runc
 COPY . /go/src/github.com/containerd/containerd
 
 WORKDIR /go/src/github.com/containerd/containerd