Add wrapX override support for ol.source.Cluster

It was not possible to override the wrapX option for the cluster source.
This commit adds that functionality.

externs/olx.js

@@ -3684,7 +3684,8 @@ olx.source.BingMapsOptions.prototype.wrapX;
  *     format: (ol.format.Feature|undefined),
  *     logo: (string|undefined),
  *     projection: ol.proj.ProjectionLike,
- *     source: ol.source.Vector}}
+ *     source: ol.source.Vector,
+ *     wrapX: (boolean|undefined)}}
  * @api
  */
 olx.source.ClusterOptions;
@@ -3746,6 +3747,14 @@ olx.source.ClusterOptions.prototype.projection;
 olx.source.ClusterOptions.prototype.source;
 
 
+/**
+ * WrapX. Default is true
+ * @type {boolean|undefined}
+ * @api
+ */
+olx.source.ClusterOptions.prototype.wrapX;
+
+
 /**
  * @typedef {{preemptive: (boolean|undefined),
  *            url: string}}

src/ol/source/clustersource.js

@@ -28,7 +28,8 @@ ol.source.Cluster = function(options) {
     attributions: options.attributions,
     extent: options.extent,
     logo: options.logo,
-    projection: options.projection
+    projection: options.projection,
+    wrapX: options.wrapX
   });
 
   /**