tests: fix warning with old GCC about missing struct initializer

Old GCC isn't happy about the {0} initializer because the first
field in the struct is itself a struct.

../../tests/openvzutilstest.c: In function 'testReadNetworkConf':
../../tests/openvzutilstest.c:101:12: error: missing braces around initializer [-Werror=missing-braces]
     struct openvz_driver driver = {0};
            ^

This fixes commit 4a4132b4Signed-off-by: NDaniel Berrange <berrange@localhost.localdomain>

tests/openvzutilstest.c

@@ -98,10 +98,10 @@ testReadNetworkConf(const void *data G_GNUC_UNUSED)
         "    </interface>\n"
         "  </devices>\n"
         "</domain>\n";
-    struct openvz_driver driver = {0};
-
-    driver.xmlopt = openvzXMLOption(&driver);
-    driver.caps = openvzCapsInit();
+    struct openvz_driver driver = {
+        .xmlopt = openvzXMLOption(&driver),
+        .caps = openvzCapsInit(),
+    };
 
     if (!(def = virDomainDefNew()))
         goto cleanup;