test-backface-culling: Use the experimental pipeline API
test-backface-culling: Use the experimental pipeline API

This tweaks the backface culling test to use the experimental pipeline
API as well as the legacy API. All of the primitives are now rendered
with all 16 combinations of front winding, cull face mode and legacy
state.

The test to 'draw a regular rectangle' has been removed. I think this
initially existed because their were different functions to draw a
rectangle with and without texturing. This is no longer the case so it
is no longer useful and it's awkward to implement because it need a
separate pipeline to disable the texturing.

https://bugzilla.gnome.org/show_bug.cgi?id=663628

Reviewed-by: Robert Bragg <12e9293ec6b30c7fa8a0926af42807e929c1684f@linux.intel.com>

djdeath/cogl,djdeath/cogl,djdeath/cogl-android,gcampax/cogl,djdeath/cogl-android,gcampax/cogl,gcampax/cogl,Distrotech/cogl,Distrotech/cogl,djdeath/cogl-android,collects/cogl,djdeath/cogl,collects/cogl,Distrotech/cogl,Distrotech/cogl,gcampax/cogl