Created by: DannyIsFunny

【Issue】 __model__ file of Paddle-Lite‘s consumes too much space.

model v45:
Anakin __model__ part : 20K
Paddle-Lite __model__: 200K

【Effect of Current PR】 Abandon op_callstack attribute from __model__, as this attribute contains too much debug info which has no effect on inference process. 【Experiment】

v45.nb:
     Before: 899K 
     After: 641k
Size of __model__ module will be reduced by 1/3