Missing xlib support about anvil

[jhasse]

Wouldn't it be better to use SDL2 instead?

I can tell you that Xlib is a nightmare to work with.

[DominikWitczakAMD]

Thanks for the suggestion.

Our library is designed to act as a bottom-most interface binding the system and the app, so adding another layer of abstraction should only happen if really necessary. It adds additional project maintenance burden which we would like to strongly avoid.

Another reason for the fact we're going to need Xlib support built-in directly ijnto Anvil is the fact that, for Vulkan, we're going to need to have the render surface wrapper extended to make use of the VK_KHR_xlib_surface extension. I'm not sure if SDL2 exposes all the handles we need to make that happen.