ci: debian-clang: build more drivers

Add gallium drivers: i915 + asahi
Add vulkan drivers: swrast + panfrost

These can now compile with the current no-error list

Reviewed-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Reviewed-by: Emma Anholt <emma@anholt.net>
Part-of: <!14289>