[PATCH] support: Link links-dso-program-c against libgcc_s

[Florian Weimer]

* Florian Weimer:

> If C++ support is not available, links-dso-program-c is used
> instead of the C++ version.  The C version was not linked against
> libgcc_s, which meant that thread cancellation and the backtrace
> function did not work in containers tests in that situation.

Sadly this breaks bootstrap.  I'm looking at a fix.

Thanks,
Florian