[Intel-gfx] [PATCH] drm/i915: add Makefile magic for testing headers are self-contained

[Chris Wilson]

Quoting Jani Nikula (2019-04-03 11:06:36)
> The below commits added dummy files to test that certain headers are
> self-contained, i.e. compilable as standalone units:
> 
> 39e2f501c1b4 ("drm/i915: Split struct intel_context definition to its own header")
> 3a891a626794 ("drm/i915: Move intel_engine_mask_t around for use by i915_request_types.h")
> 8b74594aa455 ("drm/i915: Split out i915_priolist_types into its own header")
> 
> The idea is fine, but the implementation is a bit tedious and
> inflexible, and does not really scale well.
> 
> Implement the same in make using autogenerated dummy sources to include
> the headers.

Also wants
i915/.gitignore: header_test_*.c
-Chris