Handle libstdc++ header assert messages

[tysmith]

Bug 1270832 turn on debug mode for libstdc++ headers is now helping us find issues but the assertion message is not parsed. It can be found in stdout and looks like this:

/builds/worker/fetches/sysroot-x86_64-linux-gnu/usr/lib/gcc/x86_64-linux-gnu/8/../../../../include/c++/8/bits/stl_algo.h:3721: const _Tp &std::clamp(const _Tp &, const _Tp &, const _Tp &) [_Tp = double]: Assertion '!(__hi < __lo)' failed.

I assume there are other messages as well