HEADS UP: png updated to 1.4.2

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

Hi!

I've just committed the update for png from 1.2.x to 1.4.2. I've run
multiple limited bulk builds[1][2] to identify and fix problems
introduced with this change. I've committed the patches needed with
the PKGREVISION bump commit.

Some packages didn't build for me for other reasons (e.g. not
available for amd64 or unrelated breakage), so some packages may be
broken with this libpng update. If you find any, please send a PR and
mention png in the Subject, I'll take a look.

Thanks,
 Thomas


[1] fixing lots of stuff I hadn't intended to touch ;)
[2] Statistics for last one:
Total number of packages:       2449
Successfully built:             2335
Failed build:                   49
Depending on failed package:    11
Explicitly broken or masked:    23
Depending on masked package:    31