fix compilation error against llvm/clang trunk

tried to compile Crisp against the latest llvm/clang trunk, but found compilation errors.

it started with this compiler error:

> 'llvm/Target/TargetData.h' file not found

and concluded, that the whole type was reworked. the relevant commits are these:

> ------------------------------------------------------------------------
> r165404 | mvillmow | 2012-10-08 18:40:38 +0200 (Mon, 08 Oct 2012) | 1 line
>
> Move TargetData to DataLayout.
> ------------------------------------------------------------------------
> r165403 | mvillmow | 2012-10-08 18:39:34 +0200 (Mon, 08 Oct 2012) | 1 line
>
> Move TargetData to DataLayout.
> ------------------------------------------------------------------------
> r165402 | mvillmow | 2012-10-08 18:38:25 +0200 (Mon, 08 Oct 2012) | 1 line
>
> Move TargetData to DataLayout.
> ------------------------------------------------------------------------
> r165401 | mvillmow | 2012-10-08 18:37:04 +0200 (Mon, 08 Oct 2012) | 1 line
>
> Move TargetData to DataLayout.