Fixed compile bug

kernel.cpp: In function ‘bool CheckProofOfStake(const CTransaction&, unsigned int, uint256&, uint256&)’:
kernel.cpp:418:65: error: expected ‘;’ before ‘:’ token
kernel.cpp:418:65: error: expected primary-expression before ‘:’ token
kernel.cpp:418:65: error: expected ‘;’ before ‘:’ token
kernel.cpp:425:180: error: expected ‘:’ before ‘;’ token
kernel.cpp:425:180: error: expected primary-expression before ‘;’ token