xcore backend: add pattern for CP offset memory fetch

[Richard Osborne]

Thanks,

Applied in r185518 (with some further test case minimisation).

On 3 Jul 2013, at 07:53, Robert Lytton <robert at xmos.com> wrote:

> Hi Richard,
> 'specific' multiclass is unrolled.
> test case moved into load.ll
> thank you
> robert