Fix docker builds (#9805)

* move docker test logic to share/spack/qa
* update Dockerfile for archlinux

share/spack/qa/run-docker-tests

@@ -0,0 +1,48 @@
+#!/bin/bash -e
+#
+# Copyright 2013-2018 Lawrence Livermore National Security, LLC and other
+# Spack Project Developers. See the top-level COPYRIGHT file for details.
+#
+# SPDX-License-Identifier: (Apache-2.0 OR MIT)
+
+#
+# Description:
+#     Runs Spack docker tests.  This builds a docker image for each of the
+#     configurations in share/spack/docker/config.
+#
+# Usage:
+#     run-docker-tests
+#
+
+__login_attempted=0
+__login_success=1
+ensure_docker_login() {
+    if [ "$__login_attempted" '!=' '0' ] ; then
+        return $__login_success
+    fi
+
+    echo "$DOCKER_PASSWORD" | \
+        docker login -u "$DOCKER_USERNAME" --password-stdin
+
+    if [ $? '=' '0' ] ; then
+          __login_success=0
+    fi
+
+    __login_attempted=1
+    return $__login_success
+}
+
+for config in share/spack/docker/config/* ; do
+    source "$config" ;
+    ./share/spack/docker/build-image.sh;
+done
+
+if [ "$TEST_SUITE" '=' "docker build" -a \
+     "$TRAVIS_EVENT_TYPE" != "pull_request" -a \
+     ensure_docker_login ] ; then
+
+    for config in share/spack/docker/config/* ; do
+        source "$config"
+        ./share/spack/docker/push-image.sh
+    done
+fi