i965: Use aubinator/genxml for INTEL_DEBUG=bat commands.

i965: Use aubinator/genxml for INTEL_DEBUG=bat commands.

This should give substantially better decoding, as the public libdrm
decoder hasn't been properly maintained in years.

For now, we reuse the existing state dumping mechanism.  We'll improve
that in the next patch.

To avoid increasing the size of the driver, we restrict this feature
to debug builds of Mesa.  There's probably very little use for it in
release builds anyway.

Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>