[llvm] added a script to update llvm-mc test file (PR #107246)

[Brox Chen via llvm-commits]

broxigarchen wrote:

> This looks really useful! I wonder if we could also make it work for the error message checking?
> 
> E.g. generate the following check lines `CHECK-ERR: [[#@LINE]]:<col>: error: ...`
> 
> if the RUN: line contains something like `not llvm-mc .... 2>&1 | FileCheck`?

I was looking at it. It's currently not supporting since the `not` is interrupting the binary check. I'll try to see if I can get this to work

https://github.com/llvm/llvm-project/pull/107246