[llvm] [llvm] Add format check for MCSubtargetFeatures (PR #180943)

[Georgiy Samoylov via llvm-commits]

sga-sc wrote:

@MaskRay, gentle ping. There is a change requested from your side that is already addressed. Is there anything else I should do before merging this patch? Approves from other reviewers are collected and I'd like to merge this change without bypassing rules.

https://github.com/llvm/llvm-project/pull/180943