Function nginx::BN_GENCB_set

pub unsafe extern "C" fn BN_GENCB_set(
    gencb: *mut BN_GENCB, 
    callback: Option<unsafe extern "C" fn(arg1: c_int, arg2: c_int, arg3: *mut BN_GENCB) -> c_int>, 
    cb_arg: *mut c_void
)