[compiler-rt] [compiler-rt][ubsan][nfc-ish] Fix a type conversion bug (PR #100665)

[via llvm-commits]

llvmbot wrote:

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Failed to cherry-pick: 25f9415713f9f57760a5322876906dc11385ef8e

https://github.com/llvm/llvm-project/actions/runs/10103888499

Please manually backport the fix and push it to your github fork.  Once this is done, please create a [pull request](https://github.com/llvm/llvm-project/compare)

https://github.com/llvm/llvm-project/pull/100665