docker: Fix return code of build_qemu()

Without "set -e", the "&&" makes sure that the return code reflects the
result status, and that make only runs if configure succeeds.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <20170905025614.579-2-famz@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Based-on: 20170905021201.25684-1-famz@redhat.com

tests/docker/common.rc

@@ -30,6 +30,5 @@ build_qemu()
                  $@"
     echo "Configure options:"
     echo $config_opts
-    $QEMU_SRC/configure $config_opts
-    make $MAKEFLAGS
+    $QEMU_SRC/configure $config_opts && make $MAKEFLAGS
 }