Flatpak with Vulkan (reloaded)

[mbugni]

Following my previous release I managed to build the Vulkan version v1.5.1 again.

The build is successful, but if I (try to) start the app I get:

----- R_InitOpenGL -----
r_vidMode reset from 27 to 0.
Initializing Vulkan subsystem
Enabled Vulkan instance extensions:
    VK_EXT_debug_utils
    VK_KHR_xlib_surface
    VK_KHR_surface
    VK_KHR_get_physical_device_properties2
Enabled Vulkan layers:
Enabled Vulkan device extensions:
    VK_KHR_fragment_shading_rate
    VK_KHR_buffer_device_address
    VK_EXT_descriptor_indexing
    VK_KHR_maintenance1
    VK_KHR_synchronization2
    VK_KHR_swapchain
Unknown command 'vid_restart'
Sys_Error: Failed to create a Vulkan physical device, error code = VK_ERROR_FEATURE_NOT_PRESENT

This is very similar to my previous issue.

Since I'm fine with the OpenGL version, I won't spend more time with Vulkan.
Maybe someone would take over my version and publish the app on Flathub.

Regards

[RobertBeckebans]

I will look into this in the next weeks as RBDOOM 1.6.0 is near completion. I already forked your repo at https://github.com/RobertBeckebans/RBDOOM-3-BFG_Flatpak