Function SCIPsetChgLongintParam 

pub unsafe extern "C" fn SCIPsetChgLongintParam(
    set: *mut SCIP_SET,
    messagehdlr: *mut SCIP_MESSAGEHDLR,
    param: *mut SCIP_PARAM,
    value: c_longlong,
) -> SCIP_RETCODE

changes the value of an existing SCIP_Longint parameter