Add experimental support for DXVK-native on Linux

[Sanakan8472]

This allows compiling the DX11 renderer on Linux. The main goal is to make it easier to make renderer changes on Linux without having to boot Windows. To use:

1. Clone DXVK
2. Change meson.build to lib_glfw = dependency('glfw3', required: false) instead of just 'glfw'.
3. Run ./package-native.sh master ~/libDXVK --no-package
4. export PKG_CONFIG_PATH="~/libDXVK/dxvk-native-master/usr/lib/pkgconfig"
5. Enable EZ_BUILD_EXPERIMENTAL_DXVK

Note that you won't be able to run this without considerable effort so right now it's merely to make sure the code compiles:

1. There is no shader compiler so if you want to run DX11, you need to get a shader cache from a Windows machine or from the Windows CI build artifacts.
2. We conflict between two GLFW versions as EZ does not use the system version but DXVK does. You can delete our version and replace it with the system version but it's tedious.
3. For some reason you can't load two renderers at the same time under Linux. Sub-system init for DX11 is simply skipped. Can't figure out why.
4. Latest release of dxvk has a bug, so you need to apply at least this patch: Fixed GLFW exception at startup doitsujin/dxvk#4061
5. You need to set the env var DXVK_WSI_DRIVER=GLFW before running any app.

[jankrassnigg]

Sounds like great fun.

[Sanakan8472]

Sounds like great fun.

Anything is more fun than having to boot windows all the time...