[llvm] [Utils][update_mc_test_checks] Generate check lines in alphabetical order. (PR #164424)

[Joe Nash via llvm-commits]

https://github.com/Sisyph commented:

The goal sounds good to me. 
I guess there will be some one time pain associated with this change. It seems likely to change the order of CHECKS when you run it on a file, so any code change that affects a MC test file generated with this script should likely have a precommit running this new version on the test file.
Consider it a +1 from me, please wait for another reviewer. 

https://github.com/llvm/llvm-project/pull/164424