los0-gc.lisp is heavily debug-instrumented

I just thought I'd mention that for a couple of months now, the
stop-and-copy in los0-gc.lisp has been instrumented with debugging
code that is quite unreasonable for any sort of normal use. It's
randomly migrating code-vectors to newspace, to mention one
thing. While I do expect GC/memory-management eventually to be
"plug-and-play" by default, that's not quite the case at the moment
(although in principle just removing all that debugging stuff from the
current stop-and-copy should work well. (defun simple-stop-and-copy)
is an approximation to that).

-- 
Frode Vatvedt Fjeld