Fix dtoa for +nan.0 +inf.0 -inf.0
Fix dtoa for +nan.0 +inf.0 -inf.0

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