Defined but not used in TcPatSyn

[Edward Z. Yang]

Judging from affect files, probably

commit c269b7e85524f4a8be3cd0f00e107207ab9197af
Author: Dr. ERDI Gergo <gergo at erdi.hu>
Date:   Thu Apr 10 22:13:00 2014 +0800

    Split off pattern synonym definition checking from pattern inversion

Edward

Excerpts from Joachim Breitner's message of 2014-04-11 13:19:06 -0700:
> Hi,
> 
> someone introduced a validate error recently:
> 
> compiler/typecheck/TcPatSyn.lhs:324:19:
>     Warning: Defined but not used: `lit'
> 
> compiler/typecheck/TcPatSyn.lhs:325:17:
>     Warning: Defined but not used: `n'
> 
> 
> Greetings,
> Joachim