[Piglit] Plan for enabling more tests in concurrent mode

[Chris Forbes]

> BTW, we are hoping to reduce the use of glutKeyboardFunc as much as possible
> because it gets in the use of Waffle, so if you happen to notice some
> opportunities to get rid of glutKeyboardFunc entirely (or at least take some
> steps in that direction), feel free.

There are still a bunch of tests which are actually usefully
interactive in non-auto mode -- what's the accepted way of dealing
with those?
Rendering all the possibilities in a grid in one frame seems vaguely reasonable.

> Are you talking about adding calls to the piglit_*_projection functions, or
> simply moving the existing calls from the reshape functions to
> piglit_display so that the reshape functions can be removed?  I'm definitely
> in favor of the latter.  But adding piglit_*_projection function calls is
> problematic because those functions rely on deprecated functionality, and
> we're trying as much as possible to reduce Piglit's dependence on deprecated
> functionality so that we can start testing GLES 2.0, GLES 3.0, and forward
> compatible contexts.

Still better to have the deprecated calls in *one* place that can be
converted to setting uniforms than having
glMatrixMode/glLoadIdentity/glOrtho sprayed everywhere, though, isn't
it?

-- Chris