rendervulkan: Fix UB caused by undersized struct definition

[Starsam80]

Taken from the upstream mesa definition here. Below is a "backtrace", or my best effort in trying to explain where it went wrong.

• gamescope crashes with

[gamescope] [Error] vulkan: vkGetMemoryFdKHR failed (VkResult: -2)
[gamescope] [Error] vulkan: failed to allocate buffer for KMS
vulkan_make_output failed

• mesa/RADV returns -2 (VK_ERROR_OUT_OF_DEVICE_MEMORY) because of these lines
• libdrm calls DRM_IOCTL_PRIME_HANDLE_TO_FD which results in -1 (EPERM (Operation not permitted))
• the kernel seems to return that error because of this (the bo->flags & AMDGPU_GEM_CREATE_VM_ALWAYS_VALID in particular)
• mesa sets that flag here
• This is where I get a little confused (and where the UB happens)... I set a breakpoint on this line, and flags gets set to 0x660 which is at least RADEON_FLAG_NO_INTERPROCESS_SHARING | RADEON_FLAG_PREFER_LOCAL_BO. (I have yet to look at the disassembly for a reasonable explanation)
• wsi_info in mesa comes from the VK_STRUCTURE_TYPE_WSI_MEMORY_ALLOCATE_INFO_MESA gamescope sets in these lines
• wsi_info->dma_buf_sync_file is undefined because the gamescope struct does not have that field

[Starsam80]

I've been so focused on tracking this bug down that I forgot to check the other structs. wsi_image_create_info also is different, but seems to be backwards compatible to some extent. Should I change that one too? I've also been wondering if gamescope should even be using "mesa-internal" structs, it just seems like a bad idea (like the reason for the existence of this PR). Should I just remove the structs from gamescope?

[misyltoad]

The structs are unfortunately needed to make Gamescope work without modifiers