audit: properly encode device path in cgroup audit

https://bugzilla.redhat.com/show_bug.cgi?id=922186

Commit d04916fa introduced a regression in audit quality - even
though the code was computing the proper escaped name for a
path, it wasn't feeding that escaped name on to the audit message.
As a result, /var/log/audit/audit.log would mention a pair of
fields class=path path=/dev/hpet instead of the intended
class=path path="/dev/hpet", which in turn caused ausearch to
format the audit log with path=(null).

* src/conf/domain_audit.c (virDomainAuditCgroupPath): Use
constructed encoding.
Signed-off-by: NEric Blake <eblake@redhat.com>

src/conf/domain_audit.c

 /*
  * domain_audit.c: Domain audit management
  *
- * Copyright (C) 2006-2012 Red Hat, Inc.
+ * Copyright (C) 2006-2013 Red Hat, Inc.
  * Copyright (C) 2006 Daniel P. Berrange
  *
  * This library is free software; you can redistribute it and/or
@@ -682,8 +682,8 @@ virDomainAuditCgroupPath(virDomainObjPtr vm, virCgroupPtr cgroup,
     rdev = virDomainAuditGetRdev(path);
 
     if (!(detail = virAuditEncode("path", path)) ||
-        virAsprintf(&extra, "path path=%s rdev=%s acl=%s",
-                    path, VIR_AUDIT_STR(rdev), perms) < 0) {
+        virAsprintf(&extra, "path %s rdev=%s acl=%s",
+                    detail, VIR_AUDIT_STR(rdev), perms) < 0) {
         VIR_WARN("OOM while encoding audit message");
         goto cleanup;
     }