add docker as builder

docker/Dockerfile

@@ -0,0 +1,32 @@
+FROM debian:buster
+
+COPY sources.list /etc/apt/sources.list
+
+RUN apt-get update &&\
+    apt-get install -y \
+        sudo time git-core subversion build-essential g++ bash make \
+        libssl-dev patch libncurses5 libncurses5-dev zlib1g-dev gawk \
+        flex gettext wget unzip bzip2 xz-utils device-tree-compiler python python-distutils-extra \
+        python3 python3-distutils-extra python3-setuptools swig rsync curl \
+        libsnmp-dev liblzma-dev libpam0g-dev cpio rsync gcc-multilib && \
+    apt-get clean && \
+    useradd -m builder && \
+    echo 'user ALL=NOPASSWD: ALL' > /etc/sudoers.d/builder
+
+# set system wide dummy git config
+RUN git config --system user.name "builder" && git config --system user.email "builder@example.com"
+
+USER builder
+
+VOLUME /work
+VOLUME /work/ib
+
+ENV WORK_SOURCE=/work
+ENV WORK_TARGET=x86_64
+
+COPY build.sh /bin/build.sh
+
+WORKDIR /work
+
+ENTRYPOINT [ "/bin/build.sh" ]
+