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

[Stephen Tozer via llvm-commits]

SLTozer wrote:

Updated this to try and de-duplicate, does it look better like this? The git diff doesn't look especially clean, but hopefully it's clear from the new sizes of the public functions (for crash dumps and debugify respectively) that most of the logic is now shared. Still not sure about testing, but there is one lit test that tests crash dump output, and from manually crashing the compiler a few times it looks to output exactly the same as before.

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