Merge remote-tracking branch 'remotes/famz/tags/docker-pull-request' into staging

# gpg: Signature made Tue 28 Feb 2017 12:40:00 GMT
# gpg:                using RSA key 0xCA35624C6A9171C6
# gpg: Good signature from "Fam Zheng <famz@redhat.com>"
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 5003 7CB7 9706 0F76 F021  AD56 CA35 624C 6A91 71C6

* remotes/famz/tags/docker-pull-request:
  .shippable: add s390x-cross target
  new: dockerfiles/debian-s390-cross

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

.shippable.yml

@@ -5,6 +5,8 @@ env:
       TARGET_LIST=arm-softmmu,arm-linux-user
     - IMAGE=debian-arm64-cross
       TARGET_LIST=aarch64-softmmu,aarch64-linux-user
+    - IMAGE=debian-s390x-cross
+      TARGET_LIST=s390x-softmmu,s390x-linux-user
 build:
   pre_ci:
     - make docker-image-${IMAGE}

tests/docker/dockerfiles/debian-s390x-cross.docker

@@ -0,0 +1,22 @@
+#
+# Docker s390 cross-compiler target
+#
+# This docker target is based on stretch (testing) as the stable build
+# doesn't have the cross compiler available.
+#
+FROM debian:testing-slim
+
+# Duplicate deb line as deb-src
+RUN cat /etc/apt/sources.list | sed "s/deb/deb-src/" >> /etc/apt/sources.list
+
+# Add the s390x architecture
+RUN dpkg --add-architecture s390x
+
+# Grab the updated list of packages
+RUN apt update
+RUN apt dist-upgrade -yy
+RUN apt-get build-dep -yy -a s390x qemu || apt-get -f install
+RUN apt install -yy gcc-multilib-s390x-linux-gnu binutils-multiarch
+
+# Specify the cross prefix for this image (see tests/docker/common.rc)
+ENV QEMU_CONFIGURE_OPTS --cross-prefix=s390x-linux-gnu-