Optimize EQUALP on structures with raw slots.

Optimize EQUALP on structures with raw slots.

Add a comparer slot to raw-slot-data, which is defined as
(lambda (index x y)
  (= (%raw-instance-ref/double x index)
     (%raw-instance-ref/double y index)))

Which is both faster than calling %raw-instance-ref/double out of
line and does not cons.