bug#7908: png-1.5 fix for emacs-23.2 and HEAD

[Eli Zaretskii]

> From: Chong Yidong <cyd@stupidchicken.com>
> Cc: Thomas Klausner <tk@giga.or.at>, 7908@debbugs.gnu.org
> Date: Tue, 25 Jan 2011 15:57:38 -0500
> 
> > This doesn't work, I tried that a few weeks ago, and I still get link
> > errors.
> 
> Do you have the exact link errors?  If possible, please try with this
> patch (the libpng API changes are a bit of a mess, and it's possible
> that small changes might affect success or failure).

With this patch, image.c doesn't compile:

  image.c: In function `png_load':
  image.c:5866: error: invalid type argument of `unary *'