Use scripts to reduce code size

src/ci/docker/cross/Dockerfile

@@ -19,9 +19,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   bzip2 \
   patch \
   libssl-dev \
-  pkg-config \
-  software-properties-common \
-  apt-transport-https
+  pkg-config
 
 COPY scripts/dumb-init.sh /scripts/
 RUN sh /scripts/dumb-init.sh

src/ci/docker/cross/install-x86_64-redox.sh

@@ -1,3 +1,4 @@
+#!/bin/bash
 # Copyright 2017 The Rust Project Developers. See the COPYRIGHT
 # file at the top-level directory of this distribution and at
 # http://rust-lang.org/COPYRIGHT.
@@ -8,9 +9,15 @@
 # option. This file may not be copied, modified, or distributed
 # except according to those terms.
 
+# ignore-tidy-linelength
+
 set -ex
 
+apt-get update
+apt-get install -y --no-install-recommends software-properties-common apt-transport-https
+
 apt-key adv --batch --yes --keyserver keyserver.ubuntu.com --recv-keys AA12E97F0881517F
 add-apt-repository -y 'deb https://static.redox-os.org/toolchain/apt /'
+
 apt-get update
 apt-get install -y x86-64-unknown-redox-gcc

src/ci/docker/dist-x86_64-redox/Dockerfile

@@ -1,37 +1,22 @@
 FROM ubuntu:16.04
 
-RUN apt-get update && apt-get install -y --no-install-recommends \
-  g++ \
-  make \
-  file \
-  curl \
-  ca-certificates \
-  python2.7 \
-  git \
-  cmake \
-  sudo \
-  bzip2 \
-  xz-utils \
-  wget \
-  libssl-dev \
-  pkg-config \
-  software-properties-common \
-  apt-transport-https
+COPY scripts/cross-apt-packages.sh /scripts/
+RUN sh /scripts/cross-apt-packages.sh
 
-# Install the cross compiler
-RUN apt-key adv --batch --yes --keyserver keyserver.ubuntu.com --recv-keys AA12E97F0881517F && \
-    add-apt-repository -y 'deb https://static.redox-os.org/toolchain/apt /' && \
-    apt-get update && \
-    apt-get install -y x86-64-unknown-redox-gcc
+COPY scripts/dumb-init.sh /scripts/
+RUN sh /scripts/dumb-init.sh
 
-RUN curl -OL https://github.com/Yelp/dumb-init/releases/download/v1.2.0/dumb-init_1.2.0_amd64.deb && \
-    dpkg -i dumb-init_*.deb && \
-    rm dumb-init_*.deb
 ENTRYPOINT ["/usr/bin/dumb-init", "--"]
 
-RUN curl -o /usr/local/bin/sccache \
-      https://s3.amazonaws.com/rust-lang-ci/rust-ci-mirror/2017-05-12-sccache-x86_64-unknown-linux-musl && \
-      chmod +x /usr/local/bin/sccache
+COPY scripts/crosstool-ng.sh /scripts/
+RUN sh /scripts/crosstool-ng.sh
+
+WORKDIR /tmp
+COPY cross/install-x86_64-redox.sh /tmp/
+RUN ./install-x86_64-redox.sh
+
+COPY scripts/sccache.sh /scripts/
+RUN sh /scripts/sccache.sh
 
 ENV \
     AR_x86_64_unknown_redox=x86_64-unknown-redox-ar \