Compile warning in function BoatCitaGetBlockNumber

[PanHH]

Describe the bug
Compile warning in function BoatCitaGetBlockNumber

api_cita.c: In function 'BoatCitaGetBlockNumber':
api_cita.c:557:48: warning: passing argument 3 of 'web3_cita_getBlockNumber' from incompatible pointer type [-Wincompatible-pointer-types]
                                                &result);
                                                ^

[Cavalierliu]

problem fixed