__label__ LABEL must precede all other declarations in a block about language-c

[lambdageek]

@pbreuer two notes

1. GCC documentation on "local labels" says

   Local label declarations must come at the beginning of the block, before any ordinary declarations or statements.

2. In your patch, you can use Data.Either.partitionEither :: [Either a b] -> ([a], [b]) instead of defining your own lefts, rights.

[visq]

@lambdageek, thanks for analysis.
As language-c behaves just as expected in (1), closing this issue.