`VK_KHR_maintenance4` extension is core in Vulkan 1.3. As Blender
should support Vulkan 1.2 we should not enable this extension when
it isn't available.This fixes issue to run Vulkan backend on some
platforms (Intel Iris Plus).
Maintenance4 is used to relax the interface matching rules to allow
a larger output vector to match with a smaller input vector, with
additional values being discarded.
When Maintenance4 isn't enabled a few shaders might run a tiny bit
slower as it triggers a performance notice. Users won't notice the
performance slowdown.
Pull Request: https://projects.blender.org/blender/blender/pulls/113239
6e18bb4e3e