docker: Add common.rc

"requires" checks the "FEATURE" environment for specified prerequisits,
and skip the execution of test if not found.

"build_qemu" is the central routine to compile QEMU for tests to call.
Reviewed-by: NAlex Bennée <alex.bennee@linaro.org>
Signed-off-by: NFam Zheng <famz@redhat.com>
Message-id: 1464755128-32490-8-git-send-email-famz@redhat.com

tests/docker/common.rc

+#!/bin/sh
+#
+# Common routines for docker test scripts.
+#
+# Copyright (c) 2016 Red Hat Inc.
+#
+# Authors:
+#  Fam Zheng <famz@redhat.com>
+#
+# This work is licensed under the terms of the GNU GPL, version 2
+# or (at your option) any later version. See the COPYING file in
+# the top-level directory.
+
+requires()
+{
+    for c in $@; do
+        if ! echo "$FEATURES" | grep -wq -e "$c"; then
+            echo "Prerequisite '$c' not present, skip"
+            exit 0
+        fi
+    done
+}
+
+build_qemu()
+{
+    $QEMU_SRC/configure \
+        --target-list="${TARGET_LIST}" \
+        --prefix="$PWD/install" \
+        "$@"
+    make $MAKEFLAGS
+}