Draft: Port s3 graphics driver code from @gdwnldsksc

[RaymiiOrg]

This is a WIP branch to keep track of the S3 changes in https://github.com/gdwnldsKSC/es40

To test it you need the 86c764x1.bin video driver:

  pci0.1 = s3
  {
    rom = "rom/86c764x1.bin";
  }

Startup shows a black screen with blinking cursor. Console log:

bus 0, slot 1 -- vga -- S3 Trio64/Trio32
bus 0, slot 3 -- pka -- NCR 53C810
starting drivers

DB014-B_Trio32_Trio64_Graphics_Accelerators_Mar1995.pdf