sync pow_tests.cpp / MVFCheckOverflowCalculation_test to MVF-BU
sync pow_tests.cpp / MVFCheckOverflowCalculation_test to MVF-BU
BTCfork/hardfork_prototype_1_mvf-core,BTCfork/hardfork_prototype_1_mvf-core,BTCfork/hardfork_prototype_1_mvf-core,BTCfork/hardfork_prototype_1_mvf-core,BTCfork/hardfork_prototype_1_mvf-core,BTCfork/hardfork_prototype_1_mvf-core