[clang] [llvm] [Utils] add --update-tests flag to llvm-lit (PR #97369)

[Henrik G. Olsson via cfe-commits]

hnrklssn wrote:

Added tests and updated the script. Instead of only being a free-standing script it's now (along with the UTC scripts) integrated into llvm-lit to automatically detect which script can update a failing test, using the new flag `--update-tests`.

https://github.com/llvm/llvm-project/pull/97369