bug#6415: 23.1.50; edebug-eval-defun errors on dotted pair in some macros

[Geoff Gole]

When presented with a reasonable defun form containing an unevaluated
dotted pair, edebug-eval-defun fails with

  Invalid read syntax: "Dotted spec required."

I *think* that this is an error in the cl.el debug specs and not
edebug itself. Unfortunately that's hard to verify by stepping
edebug.el as said debug specs are largely incomprehensible.

To reproduce:

  emacs -Q
  insert (defun bug () (destructuring-bind (x . y)))
  C-u C-M-x

GNU Emacs 23.1.50.1 (i686-pc-linux-gnu, GTK+ Version 2.12.11) of 2009-07-30