[m-rev.] Suggest removing extras/graphics/samples/pent

[Julien Fischer]

Hi Fabrice,

On Fri, 7 Jan 2022, Fabrice Nicol wrote:

> The sample in extras/graphics/samples/pent can no longer be built as it 
> depends on 'mtogl', the Mercury binding to the Tk widget 'togl', which was 
> removed from the distribution in 2010 (HISTORY: 3690).
>
> I would suggest removing this sample accordingly.

I vaguely recall having the intention of re-writing that example to use
glut at the time togl support was dropped.  Since that still hasn't
happened I think we can just get rid of it.

Julien.