Patch to update URLs in sequence point docs

[Jeffrey A Law]

  In message <Pine.LNX.4.30.0011251523390.25830-100000@kern.srcf.societies.cam.
ac.uk>you write:
  > This patch updates the reference to Clive Feather's Annex S to refer
  > to the latest version and adds a couple more sequence point
  > references.  It passes "make info".  OK to commit?
  > 
  > 2000-11-25  Joseph S. Myers  <jsm28@cam.ac.uk>
  > 
  > 	* invoke.texi: Update sequence points references.
This is fine.  Please install this patch if you haven't done so already.

jeff