headers_check.pl currently emits some spurious warnings, especially for
the drm headers, about using __[us]{8,16,32,64} types without including
linux/types.h.  Recursively search for types.h inclusion, avoiding
circular references.

Signed-off-by: Bobby Powers <bobbypowers@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Dave Airlie <airlied@linux.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>