examples: fix dynamic_handles.c when STARPU_NMAXBUFS is not the default value

STARPU_NMAXBUFS is set to 8 by default, but if --enable-maxbuffers is set
to a different value we need to use STARPU_NMAXBUFS when checking if
the number of buffers is correct.

This fixes examples/basic_examples/dynamic_handles.c

examples/basic_examples/dynamic_handles.c

@@ -40,7 +40,7 @@ void dummy_big_kernel(void *descr[], void *cl_arg)
 	int i;
 
 	starpu_codelet_unpack_args(cl_arg, &nb_data);
-	assert(nb_data == 9);
+	assert(nb_data == STARPU_NMAXBUFS + 1);
 	FPRINTF(stderr, "Number of data: %d\n", nb_data);
 
 	for(i=0 ; i<nb_data; i++)