[llvm] [utils] Add a script to update regclass numbers in MIR tests (PR #142761)

[Sergei Barannikov via llvm-commits]

s-barannikov wrote:

I agree with @arsenm here https://github.com/llvm/llvm-project/pull/142359#issuecomment-2939618057

While this script may be useful, it doesn't guarantee the tests don't rot over time. Unless we have an automated way to update them, that is.


https://github.com/llvm/llvm-project/pull/142761