Incorporated commit of memoize-raw.lisp made to the centaur/ branch by
Sol Swords, svn revision 1322.  An "everything" regression slowed down
slightly, as shown below, but I only changed Sol's version by
adjusting comments (after a helpful conversation with him), so since
Centaur uses memoization very heavily, I'm assuming that the slowdown
is just noise.

old:
55373.156u 1891.350s 2:30:20.21 634.8%	0+0k 1648864+4778192io 1307pf+0w

new:
55443.108u 1894.766s 2:32:05.00 628.3%	0+0k 1282408+4778376io 1023pf+0w


git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1323 5d84a466-a78b-0930-a311-59b22171a541