[tlbuild] dvisvgm build failures on Solaris

[Mojca Miklavec]

On Fri, 19 Feb 2021 at 09:00, Henri Menke wrote:
>
> If I'm not mistaken you can just unconditionally add -lrt for all
> platforms.

I'm not sure:
    https://stackoverflow.com/questions/1505402/library-not-found-for-lrt-with-qtcreator-mac-os

I checked with clang on my mac and it doesn't seem to be too happy
about the flag:
    ld: library not found for -lrt

Mojca