Added a minor optimization to avoid calling nu-rewriter-mode and
recursive-fn-on-fnstackp when not in nu-rewriter-mode.

Fixed GNUmakefile to work with Cygwin (Windows); thanks to Harsh Raju
Chamarthi for his substantial help.

Fixed a comment in *valid-output-names*.

Moved comments from (deflabel note-6-4 ...) to the note-6-4 topic in
system/doc/acl2-doc.lisp.

Quoting :doc note-6-4:

  The restrictions on utilities [oracle-apply] and [oracle-funcall]
  have been strengthened in order to avoid potentially confusing or
  inappropriate results, by imposing the following additional
  restrictions on their first argument, which must still be a
  function symbol. That symbol must not be if, synp, mv-list, or (as
  before) return-last; it must not be a key of the alist,
  *ttag-fns-and-macros*; it must not be untouchable (see
  [remove-untouchable]); and it must not be a [stobj] creator (see
  [defstobj]).


git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1182 5d84a466-a78b-0930-a311-59b22171a541

Quoting :doc note-6-4:

  The guard for system function ev-fncall-w now includes an arity
  check.


git-svn-id: http://acl2-devel.googlecode.com/svn/trunk@1183 5d84a466-a78b-0930-a311-59b22171a541