[HEADS UP] png update to 1.5 branch

[Thomas Klausner <wiz%NetBSD.org@localhost>]

Hi!

I've just committed an update for png to 1.5.1beta1 (containing a
security fix for 1.5.0, to which I originally wanted to update).
This only concerns pkgsrc-current users, 2010Q4 is not affected.

The shared library name changed, so I had to sweep pkgsrc and bump
PKGREVISIONs.

png-1.5 supposedly breaks nothing that compiled with 1.4 without
warnings.

Let me know if you find breakage anyway, I'll take a look at it.
 Thomas