Initial commit for an ubuntu 18.04 based env that can build the SDK

An initial docker image that can be used to create the SDK.  The image
has a 'buildkite-agent' user and is intended to be kept small.

Signed-off-by: Kumar Gala <kumar.gala@linaro.org>

Dockerfile

@@ -0,0 +1,16 @@
+FROM ubuntu:18.04
+
+WORKDIR /sdk-build
+
+COPY setup.sh .
+
+RUN ./setup.sh && \
+ useradd -m buildkite-agent --shell /bin/bash --uid 2000 && \
+ echo 'buildkite-agent ALL = NOPASSWD: ALL' > /etc/sudoers.d/buildkite-agent && \
+ chmod 0440 /etc/sudoers.d/buildkite-agent
+
+# Set the locale
+RUN locale-gen en_US.UTF-8
+ENV LANG en_US.UTF-8
+ENV LANGUAGE en_US:en
+ENV LC_ALL en_US.UTF-8

setup.sh

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+#!/bin/bash -e
+
+apt-get clean
+apt-get update
+
+# software-properties for add-apt-repository
+# locales for LANG support
+# sudo to make life easier when running as build user
+# vim.tiny so we have an editor
+apt-get install -y --no-install-recommends software-properties-common \
+	locales sudo vim.tiny
+
+# The package sets are based on Yocto & crosstool-ng docs/references:
+#
+# Yocto:
+# https://www.yoctoproject.org/docs/2.3.4/ref-manual/ref-manual.html#ubuntu-packages
+#
+# crosstool-ng:
+# https://github.com/crosstool-ng/crosstool-ng/blob/master/testing/docker/ubuntu18.04/Dockerfile
+apt-get install -y --no-install-recommends gcc g++ gperf bison flex texinfo \
+	help2man make libncurses5-dev python3-dev autoconf automake libtool \
+	libtool-bin gawk wget bzip2 xz-utils unzip patch libstdc++6 diffstat \
+	build-essential chrpath socat cpio python python3 \
+	python3-pip python3-pexpect debianutils iputils-ping
+
+# Install python3.8-dev for build w/GDB
+apt-get install -y --no-install-recommends python3.8-dev
+
+# Install packages for creating SDK packages
+apt-get install -y --no-install-recommends makeself p7zip-full tree curl
+
+# Install python packages to allow upload to aws S3
+pip3 install setuptools
+pip3 install awscli
+
+# Grab a new git
+add-apt-repository ppa:git-core/ppa -y
+apt-get update
+apt-get install git -y