Add missing pre_exec hook for dm

src/sched_policies/deque_modeling_policy_data_aware.c

@@ -1019,7 +1019,7 @@ struct starpu_sched_policy _starpu_sched_dm_policy =
 	.remove_workers = dmda_remove_workers,
 	.push_task = dm_push_task,
 	.pop_task = dmda_pop_task,
-	.pre_exec_hook = NULL,
+	.pre_exec_hook = dmda_pre_exec_hook,
 	.post_exec_hook = dmda_post_exec_hook,
 	.pop_every_task = dmda_pop_every_task,
 	.policy_name = "dm",