new version of coral-low.lisp

[Gregor.pa@Xerox.COM]

There is a new verion of coral-low.lisp on parcvax.xerox.com.

People using PCL in coral-lisp should get a copy of this file and use:

(compile-pcl 't)

to recompile PCL right away.  They should then recompile their code that
uses PCL.

This fix fixes a horrible bug which caused caching functions to bomb out
in mysterious ways under mysterious circumunstances.  It is conceivable
that this bug could cause PCL to write in random parts of memory.
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