Treat different behavior of s390x in valgrind_memalign

The x86 firmware keeps looping in case no bootable drives are found, but
s390x one simply shuts the machine down. Let's allow this behavior in
valgrind_memalign test.
Signed-off-by: NLukáš Doktor <ldoktor@redhat.com>

qemu/tests/cfg/valgrind_memalign.cfg

@@ -9,6 +9,10 @@
     start_vm = no
     Ubuntu:
         valgrind_install_cmd = "apt-get install -y valgrind"
+    s390x:
+        # s390 firmware quits when no-bootable devices (unlike x86)
+        extra_params += " -no-shutdown"
+        expected_status = "paused (shutdown)"
     images = ""
     nics = ""
     serials = ""

qemu/tests/valgrind_memalign.py

@@ -47,7 +47,7 @@ def run(test, params, env):
 
     time.sleep(interval)
     error.context("Verify guest status is running after cont", logging.info)
-    vm.verify_status("running")
+    vm.verify_status(params.get("expected_status", "running"))
 
     error.context("Quit guest and check the process quit normally",
                   logging.info)