bug#21428: 24.5; Crash of emacs on OS X, installed via homebrew cask

[Eli Zaretskii <eliz@gnu.org>]

> From: Rainer M Krug <Rainer@krugs.de>
> Cc: 21428@debbugs.gnu.org,  mituharu+bug-gnu-emacs-mac@math.s.chiba-u.ac.jp
> Date: Wed, 30 Sep 2015 12:37:59 +0200
> 
> Let me know if I should update from git or stay on the one I am using at
> the moment.

It's better if you update, so we are looking at the same source and
running the same code.

But note that the latest updates already changed the line numbers you
need to use to place breakpoints in xfaces.c.  Here are the updated
commands (but please double-check they are still valid, before you
start the session, and change the line numbers as necessary):

  set logging on
  break xfaces.c:4199
  commands
  bt
  continue
  end
  break xfaces.c:4320
  commands
  bt
  p c->used+1
  continue
  end
  break xfaces.c:4344
  commands
  bt
  p c->used-1
  continue
  end