* Old version was basically accessing raw slots with %INSTANCE-REF,
and doing EQUALP on the results. This was most obviously wrong
for raw slots that were larger than a word (double-floats on 32-bit
platforms). Less obviously this is also wrong for some float
corner-cases, like negative zeroes.
* Add RAW-INSTANCE-SLOTS-EQUALP which instead grovels the layout for
the slot definitions and determines the proper accessor functions
for each slot from that.
* Reported by Vjacheslav Fyodorov.