Virgil 3D with SDL2 on Windows 10 and macOS

[KJ Liew]

Hello,

At long last, Virgil 3D can be realized on Windows 10 Host for Linux VM
with host OpenGL acceleration. This is based on initial work by akihikodaki
"Virgil 3D renderer on macOS" at
https://mail.gnu.org/archive/html/qemu-devel/2021-02/msg04235.html with
improvements.

- Remove ANGLE EGL dependency and reuse existing OpenGL Core support
  from SDL2 used by Linux.
- Fix known issues with OpenGL Core and provide MINGW-packages for virglrenderer
- 2 simple, non-invasive QEMU patches, supporting both Windows 10 and
  macOS.
- Performance comparable to ANGLE OpenGL ES backend.

Addtional SDL2 fix required to workaround Apple OpenGL FBO quirk.
https://github.com/libsdl-org/SDL/issues/4986

Video captured for Windows 10 and macOS are available on YouTube:
https://youtu.be/n7cmYMJd-lA (Windows 10 21H1 Ryzen 2500U)
https://youtu.be/FVv8UjGhYPU (macOS Monterey MacBookAir M1)

All materials were published at
https://github.com/kjliew/qemu-3dfx/tree/master/virgil3d

Regards,
KJ Liew