[llvm] [Support] report_fatal_error: Do not generate crash backtrace by default (PR #128495)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm approved this pull request.

Thanks so much for doing this! This was a truly horrible default (and I would argue this should not even be an option). report_fatal_error is not an assertion and should be a clean exit 

https://github.com/llvm/llvm-project/pull/128495