networkStartNetworkVirtual: Don't leak macmap object

When starting network a macmap object is created (which stores
MAC -> domain name mappings). However, if something goes wrong
(e.g. virNetDevIPCheckIPv6Forwarding() fails) then the object is
leaked.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>
Reviewed-by: NErik Skultety <eskultet@redhat.com>

src/network/bridge_driver.c

@@ -2453,6 +2453,7 @@ networkStartNetworkVirtual(virNetworkDriverStatePtr driver,
         goto err1;
 
     virNetworkObjSetMacMap(obj, macmap);
+    macmap = NULL;
 
     /* Set bridge options */
 
@@ -2590,6 +2591,7 @@ networkStartNetworkVirtual(virNetworkDriverStatePtr driver,
         ignore_value(virNetDevTapDelete(macTapIfName, NULL));
         VIR_FREE(macTapIfName);
     }
+    virNetworkObjUnrefMacMap(obj);
     VIR_FREE(macMapFile);
 
  err0: