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

[Shafik Yaghmour via llvm-commits]

https://github.com/shafik commented:

So `report_fatal_error` is being used in so many areas I don't know if making a change to the behavior unilaterally makes sense. I do get that there is a sense that in some areas this is being used incorrectly or in an unintended way but then let's have that discussion instead first, maybe?

Then if folks in some areas decide they want a different behavior then we can decide how to provide that behavior and maybe that requires a refactor that folks can then opt into, as opposed to opting everyone into the same different behavior.

CC @AaronBallman 

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