[arch-dev-public] Some PNG images won't work with libpng 1.6

[Evangelos Foutras]

After moving the libpng 1.6 rebuilds to [testing], I noticed that some
PNG icons wouldn't load. In my case the broken icons belonged to
nm-applet and smplayer (both have been fixed in [extra]).

Some KDE components are probably affected but I'm not sure of the extend
there.

The plan is to run a check on the source files of all packages to better
assess the situation. (pngchecker.py can be used for that.¹)

It's not clear whether future libpng 1.6.x versions will be able to load
these, apparently invalid, PNG images.² Running optipng (which is
statically compiled against libpng 1.4) seems to fix the problematic PNG
files. I have used this workaround in smplayer.³

More information can be found in Gentoo's discussion about this issue:

http://www.gossamer-threads.com/lists/gentoo/dev/271064

¹ https://bugs.gentoo.org/show_bug.cgi?id=466190#c11
² https://bugzilla.mozilla.org/show_bug.cgi?id=841734#c3
³
https://projects.archlinux.org/svntogit/packages.git/commit/trunk?h=packages/smplayer&id=83c83d34c8872cd29ee256a5485e64f87814fc43