Quoted terminals are not escaped in --glr mode

Hi,

Happy (2.1.7) does not escape quoted terminals in Haskell:

```haskell
data GSymbol = HappyEOF | HappyTok {-!Int-} (Token) | G_Exp
| G_Exp1
| G_Term
| G_Factor
| G_Embraced__','__Exp__
deriving (Show,Eq,Ord)
```

```yacc
Embraced(o,s)
: o s o { $2 }

Factor
: int { Int $1 }
| var { Var $1 }
| Embraced(',', Exp) { Brack $1 }
```