[llvm] [DLCov] Origin-Tracking: Enable collecting and symbolizing stack traces (PR #143591)

[Jeremy Morse via llvm-commits]

https://github.com/jmorse commented:

I don't have any good ideas for making this testable -- it's fundamentally introspection on the innards of LLVM/clang, which then makes it heavily dependent on how LLVM is built. And that then means it'll have to be UNSUPPORTED in various configurations/scenarios, making coverage pretty random.

I suppose we can state: all the source-location monitoring we're planning is based on this, and it'll be covered by a public bot, so it's become obvious if this doesn't work.

https://github.com/llvm/llvm-project/pull/143591