Unfortunately, that seems to be the ugly way to handle this because
including the in-tree headers seems to not work and I yet haven't
figured out why (there were some changes back and forth so I lost track).
CFLAGS = -Wall -I $(top_srcdir) -I $(top_srcdir)/tools/include/uapi $(EXTRA_CFLAGS) $(KHDR_INCLUDES)
Acked-by: David Hildenbrand <david@xxxxxxxxxx>