[clang] [clang] print correct context for diagnostics suppressed by deduction (PR #125453)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

https://llvm-compile-time-tracker.com/compare.php?from=4eab2194872d54e2d4496135a277b1610ff33ead&to=adde9f1f8eabe4d98ba09fd978f8d152a9865347&stat=instructions:u

These performance results don't indicate an impact either.

https://github.com/llvm/llvm-project/pull/125453