vz: fixed migration in p2p mode

dom xml generated on begin step should be passed
to perform step in VIR_MIGRATE_PARAM_DEST_XML parameter.
Otherwise 'XML error: failed to parse xml document' is
raised on destination host as dom xml is NULL.
Signed-off-by: NPavel Glushchak <pglushchak@virtuozzo.com>

src/vz/vz_driver.c

@@ -3199,6 +3199,7 @@ vzDomainMigratePerformP2P(virDomainObjPtr dom,
     virConnectPtr dconn = NULL;
     virTypedParameterPtr params = NULL;
     int ret = -1;
+    int maxparams = nparams;
 
     if (virTypedParamsCopy(&params, orig_params, nparams) < 0)
         return -1;
@@ -3210,6 +3211,10 @@ vzDomainMigratePerformP2P(virDomainObjPtr dom,
                                              &cookieout, &cookieoutlen)))
         goto done;
 
+    if (virTypedParamsAddString(&params, &nparams, &maxparams,
+                                VIR_MIGRATE_PARAM_DEST_XML, dom_xml) < 0)
+        goto done;
+
     cookiein = cookieout;
     cookieinlen = cookieoutlen;
     cookieout = NULL;