Add/enable libbacktrace in containers with LLVM backend

[eine]

Coming from ghdl/ghdl#1578

/cc @tmeissner

[abyszuk]

Can we use libbacktrace from here
I did some googling and it looks like Ian's repo is the original source of this library. It was later included in the GCC sources, but the upstream seems to still be this version.
It should be also cleaner solution that copying GCC sources for each build.
README mentions that it supports also MacOS, so it should fix ghdl/ghdl#1693 too

The problem is that libbacktrace.a isn't compiled and installed by default in GCC releases, so we can't use system version.
AFAIK only Debian patches their GCC build to include it, but I couldn't find it in the Fedora RPMs for example.