drop unused field

src/datawizard/coherency.h

@@ -179,9 +179,6 @@ struct _starpu_data_state
 	/* what is the default write-through mask for that data ? */
 	uint32_t wt_mask;
 
-	/* allows special optimization */
-	uint8_t is_readonly;
-
 	/* in some case, the application may explicitly tell StarPU that a
  	 * piece of data is not likely to be used soon again */
 	unsigned is_not_important;

src/datawizard/filters.c

@@ -232,7 +232,6 @@ static void _starpu_data_partition(starpu_data_handle_t initial_handle, starpu_d
 		child->is_not_important = initial_handle->is_not_important;
 		child->wt_mask = initial_handle->wt_mask;
 		child->home_node = initial_handle->home_node;
-		child->is_readonly = initial_handle->is_readonly;
 
 		/* initialize the chunk lock */
 		_starpu_data_requester_list_init(&child->req_list);