[refactor] proceed return values from C functions in OP_RET block
[refactor] proceed return values from C functions in OP_RET block

picrin-scheme/picrin,leavesbnw/picrin,ktakashi/picrin,koba-e964/picrin,dcurrie/picrin,dcurrie/picrin,leavesbnw/picrin,ktakashi/picrin,picrin-scheme/picrin,leavesbnw/picrin,koba-e964/picrin,omasanori/picrin,omasanori/picrin,koba-e964/picrin,ktakashi/picrin