[clang] [compiler-rt] [ubsan] Display correct runtime messages for negative _BitInt (PR #93612)

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earnol wrote:

@mstorsjo It seems your compiler build does not have int128_t enabled. Could you please test https://github.com/llvm/llvm-project/pull/96240 in your environment to verify it has no such problem?

https://github.com/llvm/llvm-project/pull/93612