ConnectBlock(): fix error() format to be unsigned
ConnectBlock(): fix error() format to be unsigned

- I introduced the wrong format macro with my former patch (#2018), this
  needs to be signed not unsigned (thanks Luke-Jr)

jlay11/sharecoin,ghostlander/Testcoin,ghostlander/Testcoin,jlay11/sharecoin,jlay11/sharecoin,ghostlander/Testcoin,jlay11/sharecoin,jlay11/sharecoin,ghostlander/Testcoin,jlay11/sharecoin