message: Include smart_contract.png in makefile for Gitian
diff: @@ -309,6 +309,7 @@ RES_ICONS = \
  qt/res/icons/staking_off.png \
  qt/res/icons/contract_input.png \
  qt/res/icons/contract_output.png \
  + qt/res/icons/smart_contract.png \
  qt/res/icons/lock_staking.png
  BITCOIN_QT_BASE_CPP = \
  