[clang] [compiler-rt] Fix "[clang][UBSan] Add implicit conversion check for bitfields" (PR #87761)

[Vitaly Buka via cfe-commits]

vitalybuka wrote:

ok
please paste here what ever looks like real failure from the patch
buildbot does not sent me, as I am not on the blame list

https://github.com/llvm/llvm-project/pull/87761