[llvm] [TableGen] Rework error reporting for duplicate Feature/Processor. (PR #102257)

[Sergei Barannikov via llvm-commits]

s-barannikov wrote:

> This is not ready for merge but wanted initial feedback. Specifically, `checkDuplicateRecords` needs to be moved somewhere else, but I did not find a suitable file in llvm/utils/TableGen/Common. Maybe we can add new files in there? Utils.cpp/h if we want to be generic. Or if there are other better suggestions. 

CodeGenSchedule.h is certainly not the best place for this helper. Utils.cpp/h sounds appropriate, and I'd probably consider moving LessRecordFieldName and related there too.

https://github.com/llvm/llvm-project/pull/102257