esx: Don't ignore the vcenter query parameter

Since 070f6100 the vcenter query
parameter has been ignored, because the refactoring to use
esxUtil_ParseQuery was incomplete. This effectively broke migration,
because the vcenter query parameter is essential for a migration.

src/esx/esx_driver.c

@@ -475,11 +475,18 @@ esxOpen(virConnectPtr conn, virConnectAuthPtr auth, int flags ATTRIBUTE_UNUSED)
     }
 
     /* Login to vCenter */
-    if (vCenter != NULL) {
+    if (parsedQuery->vCenter != NULL) {
         VIR_FREE(url);
         VIR_FREE(password);
         VIR_FREE(username);
 
+        vCenter = strdup(parsedQuery->vCenter);
+
+        if (vCenter == NULL) {
+            virReportOOMError();
+            goto cleanup;
+        }
+
         /* If a vCenter is specified resolve the hostname */
         if (STRNEQ(vCenter, "*") &&
             esxUtil_ResolveHostname(vCenter, vCenterIpAddress,