[clang] [ubsan] Use SanitizerOrdinal instead of SanitizerMask for EmitCheck (exactly one sanitizer is required) (PR #122511)

[Vitaly Buka via cfe-commits]

vitalybuka wrote:

I assume this is NFC[I], please make it in title
and there was not a single instance where >1 bits are set?

https://github.com/llvm/llvm-project/pull/122511