[tlbuild] PostScript support in dvisvgm for darwin(legacy)

[Karl Berry]

    official standpoint of this?

For TL, linking against libgs is always done with dlload at runtime, not
at build (link) time, precisely because those horrific libgs
dependencies are impossible to resolve.  I recently wrote about it here:
  http://tug.org/pipermail/tlbuild/2018q1/004089.html

We adopted this approach some years ago, after discovering that linking
against libgs created binaries which could not be run at all on some
systems different from the builder's, because of differences in
libstdc++, libfontconfig, etc. It is impossible to statically link
everything that is required.

Martin's answer discusses alternatives. -k