Fix KMS/DRM on ArchyPie

[V0rt3x667]

At present ArchyPie is only functional on devices that are running either x11 or Wayland. EmulationStation & AttractMode do not work under KMS/DMS on x86 and probably are not working on Raspberry Pis. The Raspberry Pi 2,3 & 4 no longer use the propriety Broadcom drivers on Arch Linux Arm. It would also be nice if x86 could also run ArchyPie without x11/Wayland where possible.

• [x] Set up Raspberry Pi 2 for testing
• [ ] Restore missing backend functions & modules from RetroPie
• [ ] Add the custom SDL 1.2 Backwards Compatibility & SDL2 libraries provided by RetroPie for KMS
• [ ] Get at least one frontend working on x86 with KMS

[V0rt3x667]

Testing on a Raspberry Pi stock SDL2 uses KMS/DRM without further modification. EmulationStation & RetroArch run fine. Attract-Mode does not however as the version of SFML shipped by Arch Linux Arm does not appear to have been built with DRM enabled. Further testing is required. A custom version of SDL2 will still be required for x86 using KMS/DRM only.