I'm not sure why you did that. Also I highly doubt we can swap out 15 for 16 at this point unless
it's a separate package. This is tantamount to a stack rebuild. Any particular reason to branch jump?

So um. I guess Herald has spoken. Sorry. >_>

I did enable SSE because Intel CPU supports it since 1999 (Pentium III) and AMD since 2001 (Athlon XP) so we can assume that a modern distro is not designed to run on computers that are more than 15 years old ! Do you know a x86-64 CPU that does not have SSE ?

Regarding the branch jump, it's simply because I did not find anything on the libpng site explaining the differences between the two branches. Since 1.5 and 1.6 seems fairly similar I don't think it's worth making a separate package.

Oh I read that as disable, my bad. They are significantly different in as much as its a complete ABI break. We'll need to investigate the required ABI compatibility for Steam first.

I guess that the 1.5 also support --enable-intel-sse=yes to be checked next time the package needs to be updated