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

[Karl Berry]

    add paths or libraries to the search
    mechanism of the dynamic linker on Mac OS. 

Some info here:
https://stackoverflow.com/questions/8137850

The man page for the Mac loader, if such still exists, should give the
option, if there is one. Maybe -rpath?
https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man1/dyld.1.html

    CFLAGS & CXXFLAGS
    to *something*, the optimisation was apparently gone completely.

It is normal and desirable for the optimization flags to be part of
C*FLAGS.

    I noticed that C[whatever]FLAGS are not always applied,
    so there might be some compiler calls without optimisation.

Indeed, ICU (?) or other packages think they know better than to follow
the convention that everyone else uses. Right, we don't worry about those.

    ship libc++ with TeX Live 

Please don't. That sounds horrible.

    I started another thread on tlbuild about this.

I can't keep threads untangled, sorry. -k