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

[Sergei Barannikov via llvm-commits]

s-barannikov wrote:

The failures do not look related and I checked that llvm-tblgen generates the same `*.inc` files before and after commit.
Still, this is the only commit that could break the bots according to the "Changes" page.
@MaskRay Could you suggest what to do in this case?


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