Fixed compiler error in https://github.com/urho3d/Urho3D/pull/1321.

Close #1322.

Source/Urho3D/Resource/ResourceCache.h

@@ -269,7 +269,7 @@ template <class T> T* ResourceCache::GetResource(const String& name, bool sendEv
 template <class T> void ResourceCache::ReleaseResource(const String& name, bool force)
 {
     StringHash type = T::GetTypeStatic();
-    static_cast<T*>(ReleaseResource(type, name, force));
+    ReleaseResource(type, name, force);
 }
 
 template <class T> SharedPtr<T> ResourceCache::GetTempResource(const String& name, bool sendEventOnFailure)