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

[Matt Arsenault via llvm-commits]

arsenm wrote:

This was https://discourse.llvm.org/t/rfc-report-fatal-error-and-the-default-value-of-gencrashdialog/73587/15

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