[arch-dev-public] [draft] nvidia-340xx and nvidia

As NVIDIA dropped support for G8x, G9x, and GT2xx GPUs with the release of 343.22, there now is set of nvidia-340xx packages supporting those older GPUs. 340xx will receive support until the end of 2019 according to NVIDIA. Users of older GPUs should consider switching to nvidia-340xx. The nvidia-343.22 and nvidia-340xx-340.46 packages will be in testing for a few days.