Nouveau Gets ARB_bindless_texture Support For Maxwell & Newer

Back for Mesa 18.0 there was OpenGL bindless textures for Kepler GPUs on the open-source NVIDIA "Nouveau" driver while now for Mesa 18.1 that support is in place for Maxwell GPUs and newer.

Bindless texture support is important for "AZDO" purposes for approaching zero driver overhead with OpenGL. ARB_bindless_texture reduces the API/GL driver overhead of resource bindings and allows accessing textures without needing to first bind/re-bind them.

The main user of the ARB_bindless_texture support on the Linux gaming desktop at the moment is Feral's port of Dawn of War III when using OpenGL. This ARB_bindless_texture support for Maxwell and newer should then allow those GPUs to work with DoW3 on Linux, but given Maxwell GPUs still lack viable re-clocking support, the performance is likely to be atrociously slow.

The support nevertheless is now in place for next quarter's Mesa 18.1 release thanks to Ilia Mirkin.