glpng patches

[James Le Cuirot]

Hello list!

I have a series of patches for glpng, resulting in an eventual bump to
version 1.46. This bump is needed as you will see and it's probably
about time, seeing as the last release was 14 years ago.

Although I have prepared these patches, not all of them are actually by
me. The most important comes from Hans de Goede, fixing CVE-2010-1519.
I think he's on this list. Hi Hans. :) A few come from Aquaria, most
notably the addition of memory reading functions.

The only other game I know of that uses this is Chromium BSU. I've
checked that it still builds and works but I've only just discovered
that most distros have opted to build it against SDL_image instead.
Gentoo still uses glpng but if I'd known that before, I might not have
spent so long on this. Oh well. :)

Regards,
James