fix mining compile error
fix mining compile error

ShadowMyst/creativechain-core,EntropyFactory/creativechain-core,ShadowMyst/creativechain-core,ShadowMyst/creativechain-core,EntropyFactory/creativechain-core,EntropyFactory/creativechain-core,EntropyFactory/creativechain-core,ShadowMyst/creativechain-core,ShadowMyst/creativechain-core,EntropyFactory/creativechain-core,ShadowMyst/creativechain-core,EntropyFactory/creativechain-core