[tlbuild] dvisvgm-3.0.1

[Karl Berry]

    I'm not proposig that TeX Live patch this file; that would be madness.

We (necessarily) patch many files in many upstream packages.
Though not, at present, this one.

    I'm just suggesting that there might be a later version of libpng code.

https://sourceforge.net/projects/libpng/files/
->
https://sourceforge.net/projects/libpng/files/libpng16/

shows that 1.6.39, which is what is in TL (thanks Akira), is the
latest. -k