Be compatible with gcc 14. (Closes: #1075057) and import NMUs

(This branch imports the two missing NMUs by copying current sid as one commit. If you have a better way to do that, feel free to do so then cherry-pick my actual bug fix.)

This error correctly notes that subpass is an integer index, not a pointer, in the underlying API: https://sources.debian.org/src/vulkan-loader/1.3.296.0-1/vulkan-headers/include/vulkan/vulkan_core.h/?hl=3720#L3703 https://registry.khronos.org/vulkan/specs/latest/man/html/VkGraphicsPipelineCreateInfo.html

Hence, the fix is to use 0 not VK_NULL_HANDLE, as done in gxr-openvr.

(This code no longer exists upstream, as they have switched this example to gulkan.)

This also adds a salsa-ci.yml file, but if you want to actually use it you'll need to point Settings (in the Salsa web interface) > CI/CD > General pipelines > CI/CD configuration file there. (It currently points to the upstream CI, which doesn't work here.) The lintian and blhc failures are probably pre-existing real issues, but sufficiently minor ones that they don't have to be dealt with right now.