Fix warnings.

src/core/task.c

@@ -290,7 +290,6 @@ int starpu_task_submit(struct starpu_task *task)
 
 	if (task->cl)
 	{
-		uint32_t where = task->cl->where;
 		unsigned i;
 
 		_starpu_codelet_check_deprecated_fields(task->cl);

src/datawizard/interfaces/multiformat_interface.c

@@ -705,5 +705,6 @@ static int copy_opencl_to_opencl(void *src_interface, unsigned src_node,
                                  void *dst_interface, unsigned dst_node)
 {
 /* TODO */
+	return 0;
 }
 #endif