add num gates to net struct

sim/group.lua

@@ -10,6 +10,7 @@ ffi.cdef [[
 		int* state_num;
 		int* in_queue;
 		int* update_tick;
+		int* num_gates_update;
 		struct Gate** gates_update_c;
 		int id;
 	};
@@ -50,6 +51,7 @@ function Group.new()
 	net.c.state_num = net.state_num
 	net.c.in_queue = net.in_queue
 	net.c.update_tick = net.update_tick
+	net.c.num_gates_update = net.num_gates_update
 	net.c.gates_update_c = ffi.cast("struct Gate**", 0)
 	net.c.id = net.id