add HARDFORK_RETARGET_BLOCKS, pass actual height to ActivateFork()  (sync with MVF-BU)
add HARDFORK_RETARGET_BLOCKS, pass actual height to ActivateFork()  (sync with 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