Change Docker container to bionic

Commit 117b8a45164bdb5ad2ab9e6809cbc923cffa338e requires version 6+
of i686-w64-mingw32-gcc to run the mingw builds, but Ubuntu Xenial (16.04)
supplies 5.3.1. Change the Docker container to Ubuntu Bionic (18.04) to
pick up a version that will run the tests.
diff --git a/tests/docker/bionic/Dockerfile b/tests/docker/bionic/Dockerfile
new file mode 100644
index 0000000..1d96184
--- /dev/null
+++ b/tests/docker/bionic/Dockerfile
@@ -0,0 +1,167 @@
+# Dockerfile
+#
+# Purpose
+# -------
+# Defines a Docker container suitable to build and run all tests (all.sh),
+# except for those that use a proprietary toolchain.
+
+# Copyright (C) 2006-2019, Arm Limited (or its affiliates), All Rights Reserved.
+# SPDX-License-Identifier: Apache-2.0
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#  http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+# This file is part of Mbed TLS (https://tls.mbed.org)
+
+FROM ubuntu:bionic
+
+ARG MAKEFLAGS_PARALLEL=""
+
+ENV DEBIAN_FRONTEND noninteractive
+
+RUN apt update \
+    && apt -y install software-properties-common \
+    && rm -rf /var/lib/apt/lists
+
+RUN add-apt-repository -y ppa:team-gcc-arm-embedded/ppa
+
+RUN apt-get update \
+    && apt-get -y install \
+    # mbedtls build/test dependencies
+    build-essential \
+    clang \
+    cmake \
+    doxygen \
+    gcc-arm-none-eabi \
+    gcc-mingw-w64-i686 \
+    gcc-multilib \
+    g++-multilib \
+    gdb \
+    git \
+    graphviz \
+    lsof \
+    python \
+    python3-pip \
+    python3 \
+    pylint3 \
+    valgrind \
+    wget \
+    # libnettle build dependencies
+    libgmp-dev \
+    m4 \
+    pkg-config \
+    && rm -rf /var/lib/apt/lists/*
+
+# Build a static, legacy openssl from sources with sslv3 enabled
+# Based on https://gist.github.com/bmaupin/8caca3a1e8c3c5686141 (build-openssl.sh)
+# Note: openssl-1.0.2 and earlier has known build issues with parallel make.
+RUN cd /tmp \
+    && wget https://www.openssl.org/source/old/1.0.1/openssl-1.0.1j.tar.gz -qO- | tar xz \
+    && cd openssl-1.0.1j \
+    && ./config --openssldir=/usr/local/openssl-1.0.1j no-shared \
+    && (make ${MAKEFLAGS_PARALLEL} || make -j 1) \
+    && make install_sw \
+    && rm -rf /tmp/openssl*
+ENV OPENSSL_LEGACY=/usr/local/openssl-1.0.1j/bin/openssl
+
+# Build OPENSSL as 1.0.2g
+RUN cd /tmp \
+    && wget https://www.openssl.org/source/old/1.0.2/openssl-1.0.2g.tar.gz -qO- | tar xz \
+    && cd openssl-1.0.2g \
+    && ./config --openssldir=/usr/local/openssl-1.0.2g no-shared \
+    && (make ${MAKEFLAGS_PARALLEL} || make -j 1) \
+    && make install_sw \
+    && rm -rf /tmp/openssl*
+ENV OPENSSL=/usr/local/openssl-1.0.2g/bin/openssl
+
+# Build a new openssl binary for ARIA/CHACHA20 support
+# Based on https://gist.github.com/bmaupin/8caca3a1e8c3c5686141 (build-openssl.sh)
+RUN cd /tmp \
+    && wget https://www.openssl.org/source/openssl-1.1.1a.tar.gz -qO- | tar xz \
+    && cd openssl-1.1.1a \
+    && ./config --prefix=/usr/local/openssl-1.1.1a -Wl,--enable-new-dtags,-rpath,'${LIBRPATH}' no-shared \
+    && make ${MAKEFLAGS_PARALLEL} \
+    && make install_sw \
+    && rm -rf /tmp/openssl*
+ENV OPENSSL_NEXT=/usr/local/openssl-1.1.1a/bin/openssl
+
+# Build libnettle 2.7.1 (needed by legacy gnutls)
+RUN cd /tmp \
+    && wget https://ftp.gnu.org/gnu/nettle/nettle-2.7.1.tar.gz -qO- | tar xz \
+    && cd nettle-2.7.1 \
+    && ./configure --disable-documentation \
+    && make ${MAKEFLAGS_PARALLEL} \
+    && make install \
+    && /sbin/ldconfig \
+    && rm -rf /tmp/nettle*
+
+# Build legacy gnutls (3.3.8)
+RUN cd /tmp \
+    && wget https://www.gnupg.org/ftp/gcrypt/gnutls/v3.3/gnutls-3.3.8.tar.xz -qO- | tar xJ \
+    && cd gnutls-3.3.8 \
+    && ./configure --prefix=/usr/local/gnutls-3.3.8 --exec_prefix=/usr/local/gnutls-3.3.8 --disable-shared --disable-guile --disable-doc \
+    && make ${MAKEFLAGS_PARALLEL} \
+    && make install \
+    && rm -rf /tmp/gnutls*
+ENV GNUTLS_LEGACY_CLI=/usr/local/gnutls-3.3.8/bin/gnutls-cli
+ENV GNUTLS_LEGACY_SERV=/usr/local/gnutls-3.3.8/bin/gnutls-serv
+
+# Build libnettle 3.1 (needed by gnutls)
+RUN cd /tmp \
+    && wget https://ftp.gnu.org/gnu/nettle/nettle-3.1.tar.gz -qO- | tar xz \
+    && cd nettle-3.1 \
+    && ./configure --disable-documentation \
+    && make ${MAKEFLAGS_PARALLEL} \
+    && make install \
+    && /sbin/ldconfig \
+    && rm -rf /tmp/nettle*
+
+# Build gnutls (3.4.10)
+RUN cd /tmp \
+    && wget https://www.gnupg.org/ftp/gcrypt/gnutls/v3.4/gnutls-3.4.10.tar.xz -qO- | tar xJ \
+    && cd gnutls-3.4.10 \
+    && ./configure --prefix=/usr/local/gnutls-3.4.10 --exec_prefix=/usr/local/gnutls-3.4.10 \
+        --with-included-libtasn1 --without-p11-kit \
+        --disable-shared --disable-guile --disable-doc \
+    && make ${MAKEFLAGS_PARALLEL} \
+    && make install \
+    && rm -rf /tmp/gnutls*
+ENV GNUTLS_CLI=/usr/local/gnutls-3.4.10/bin/gnutls-cli
+ENV GNUTLS_SERV=/usr/local/gnutls-3.4.10/bin/gnutls-serv
+
+# Build libnettle 3.4 (needed by gnutls next)
+RUN cd /tmp \
+    && wget https://ftp.gnu.org/gnu/nettle/nettle-3.4.1.tar.gz -qO- | tar xz \
+    && cd nettle-3.4.1 \
+    && ./configure --disable-documentation \
+    && make ${MAKEFLAGS_PARALLEL} \
+    && make install \
+    && /sbin/ldconfig \
+    && rm -rf /tmp/nettle*
+
+# Build gnutls next (3.6.5)
+RUN cd /tmp \
+    && wget https://www.gnupg.org/ftp/gcrypt/gnutls/v3.6/gnutls-3.6.5.tar.xz -qO- | tar xJ \
+    && cd gnutls-3.6.5 \
+    && ./configure --prefix=/usr/local/gnutls-3.6.5 --exec_prefix=/usr/local/gnutls-3.6.5 \
+        --with-included-libtasn1 --with-included-unistring --without-p11-kit \
+        --disable-shared --disable-guile --disable-doc \
+    && make ${MAKEFLAGS_PARALLEL} \
+    && make install \
+    && rm -rf /tmp/gnutls*
+
+ENV GNUTLS_NEXT_CLI=/usr/local/gnutls-3.6.5/bin/gnutls-cli
+ENV GNUTLS_NEXT_SERV=/usr/local/gnutls-3.6.5/bin/gnutls-serv
+
+RUN pip3 install --no-cache-dir \
+    mbed-host-tests \
+    mock