Modified emacs/acl2-doc.el to avoid leaving a buffer around for
doc.lisp upon initialization, unless one was already there before
initialization.  Thanks to Shilpi Goel for feedback leading to this
improvement.

Quoting :doc note-6-4:

  (GCL only) Improved the automatic proclaiming mechanism used for GCL
  builds, in particular to avoid computing a return type when a term
  is detected that could come from a call of [non-exec], and to do a
  more complete job for calls of [return-last].

  As requested by Sol Swords, erroneous evaluations of system function
  magic-ev-fncall that had produced a message, msg, will now also
  return that message. The following example, sent by Sol,
  illustrates the fix: before, evaluation of (magic-ev-fncall 'cons
  '(a) state nil nil) printed a message (to the comment window) and
  then returned (mv t nil), but now it returns mv t <msg>, shere
  <msg> denotes the message (printed with the [fmt] ~@ directive).


git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1155 5d84a466-a78b-0930-a311-59b22171a541
Forgot to update doc.lisp before committing to svn revision 1155.

git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1156 5d84a466-a78b-0930-a311-59b22171a541