Fix virDomainChrEquals for spicevmc

virDomainChrSourceDefIsEqual should return 'true' for
identical SPICEVMC chardevs, and those that have no source
specification.

After this change, a failed hotplug no longer leaves a stale
pointer in the domain definition.

https://bugzilla.redhat.com/show_bug.cgi?id=1162097
(cherry picked from commit b987684f)

src/conf/domain_conf.c

@@ -1590,16 +1590,17 @@ virDomainChrSourceDefIsEqual(const virDomainChrSourceDef *src,
                               tgt->data.spiceport.channel);
         break;
 
+    case VIR_DOMAIN_CHR_TYPE_SPICEVMC:
+        return src->data.spicevmc == tgt->data.spicevmc;
+
     case VIR_DOMAIN_CHR_TYPE_NULL:
     case VIR_DOMAIN_CHR_TYPE_VC:
     case VIR_DOMAIN_CHR_TYPE_STDIO:
-    case VIR_DOMAIN_CHR_TYPE_SPICEVMC:
     case VIR_DOMAIN_CHR_TYPE_LAST:
-        /* nada */
         break;
     }
 
-    return false;
+    return true;
 }
 
 void virDomainChrDefFree(virDomainChrDefPtr def)