Tweaked the mbe-as-exec mod from revisions 1307 and 1308, perhaps avoiding defeat of tail-recursion optimizations by special variable.

git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1318 5d84a466-a78b-0930-a311-59b22171a541
Brought doc.lisp up-to-date.

git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1319 5d84a466-a78b-0930-a311-59b22171a541
Modified hl-machine-hash to avoid assuming that (in CCL)
ccl::%address-of returns a fixnum, since email from Gary Byers
suggests that this could conceivably not be the case on some
platforms.  Updated related comments.  Some measurements, performed
(unlike before) with TIME moved outside the body of functions, show
that this change results in 4.60 seconds compared to 4.28 seconds
before the change, which seems quite tolerable.  An "everything"
regression didn't show any slowdown (beyond noise).  Thanks to Gary
Byers, Jared Davis, and Warren Hunt for helpful discussions.


git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1321 5d84a466-a78b-0930-a311-59b22171a541