minor fixes following cppcheck warnings

mpi/examples/filters/filter.c

@@ -168,9 +168,4 @@ int main(int argc, char **argv)
 	starpu_mpi_shutdown();
 
 	return ok;
-
-enodev:
-	FPRINTF(stderr, "WARNING: No one can execute this task\n");
-	starpu_shutdown();
-	return 77;
 }

src/core/perfmodel/perfmodel_history.c

@@ -993,7 +993,7 @@ static void dump_per_arch_model_xml(FILE *f, struct starpu_perfmodel *model, int
 
 	per_arch_model = &model->state->per_arch[comb][impl];
 	/* count the number of elements in the lists */
-	struct starpu_perfmodel_history_list *ptr = NULL;
+	struct starpu_perfmodel_history_list *ptr;
 
 	dump_reg_model_xml(f, model, comb, impl);
 

tests/datawizard/interfaces/test_interfaces.c

@@ -168,7 +168,6 @@ static int create_task(struct starpu_task **taskp, enum starpu_worker_archtype t
 		n_mics = starpu_worker_get_ids_by_type(STARPU_MIC_WORKER, mic_workers, STARPU_MAXMICDEVS);
 	}
 
-	int workerid=0;
 	int *workers;
 	static struct starpu_codelet cl;
 	starpu_codelet_init(&cl);