[clang] [Clang] Fix createConstexprUnknownAPValues to use zero offset when ceating APValue (PR #124478)

[Shafik Yaghmour via cfe-commits]

shafik wrote:

First failure looks like a flaky build issue: https://github.com/llvm/llvm-project/issues/124485

https://github.com/llvm/llvm-project/pull/124478