[clang] [clang] Don't crash when -Wformat-signedness specified (PR #162049)

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DeanSturtevant1 wrote:

Thanks for the fix. When I was testing the same fix, I noticed a discrepancy between `printf` and the `format` function in the test -- When `printf` (i.e., a variadic function) is used, no warning is emitted. This suggests that the code path that led to the -Wformat-signedness warning (%hhu = unsigned char with a bool argument) is not a path that should have been traveled.

https://github.com/llvm/llvm-project/pull/162049