[tlbuild] dvisvgm build failures on Solaris

[Mojca Miklavec]

Hi,

It turns out I was misreading the logs.

The actual error was:
    Undefined first referenced symbol in file clock_gettime
which is probably a result of a new line in the source code:
    auto now = system_clock::now().time_since_epoch();

Stackoverflow says that older versions of glibc (< 2.17) require an
additional -lrt flag to work, which would explain why the code works
everywhere else other than on the ancient Solaris OS.
    https://stackoverflow.com/questions/2418157/c-error-undefined-reference-to-clock-gettime-and-clock-settime
I checked and adding -lrt actually fixes the build.

Is there any volunteer to patch dvisvgm's configure.ac sources with
something like the following?

    check if the source code
        auto now = system_clock::now().time_since_epoch();
    can be compiled without -lrt
    if not, try again with -lrt
    => add -lrt to linker flags only if needed

(I would prefer if the patch wasn't Solaris-specific.)

Thank you,
    Mojca