[llvm] [UpdateTestChecks] Add support for SPIRV in update_llc_test_checks.py (PR #66213)

[Simon Pilgrim via llvm-commits]

RKSimon wrote:

How different would check_label_format have to be? Surely SPIRV has something similar that we can use?

I always like to see at least one use of the update script when we add a new target - please can you regenerate a suitable file in CodeGen\SPIRV to show the generated checks?

https://github.com/llvm/llvm-project/pull/66213