domain_conf: Unref video private data in virDomainVideoDefClear()

The private data for video definition is created in
virDomainVideoDefNew() and we attempt to free it in
virDomainVideoDefFree(). This seems to work, except
the free function calls clear function which zeroes
out the whole structure and thus virObjectUnref()
which is called on private data does nothing.

2,568 bytes in 107 blocks are definitely lost in loss record 207 of 213
   at 0x4A35476: calloc (vg_replace_malloc.c:752)
   by 0x50A6048: virAllocVar (viralloc.c:346)
   by 0x513CC5A: virObjectNew (virobject.c:243)
   by 0x4DC1DEE: qemuDomainVideoPrivateNew (qemu_domain.c:1337)
   by 0x51A6BD6: virDomainVideoDefNew (domain_conf.c:2831)
   by 0x51B9F06: virDomainVideoDefParseXML (domain_conf.c:15541)
   by 0x51CB761: virDomainDefParseXML (domain_conf.c:21158)
   by 0x51C5973: virDomainDefParseNode (domain_conf.c:21708)
   by 0x51C583A: virDomainDefParse (domain_conf.c:21663)
   by 0x51C58AE: virDomainDefParseFile (domain_conf.c:21688)
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NErik Skultety <eskultet@redhat.com>

src/conf/domain_conf.c

@@ -2853,6 +2853,7 @@ virDomainVideoDefClear(virDomainVideoDefPtr def)
     if (def->driver)
         VIR_FREE(def->driver->vhost_user_binary);
     VIR_FREE(def->driver);
+    virObjectUnref(def->privateData);
 
     memset(def, 0, sizeof(*def));
 }
@@ -2864,7 +2865,6 @@ void virDomainVideoDefFree(virDomainVideoDefPtr def)
         return;
 
     virDomainVideoDefClear(def);
-    virObjectUnref(def->privateData);
     VIR_FREE(def);
 }