[clang] [clang-repl] [test] Make an XFAIL more precise (PR #70991)

[Martin Storsjö via cfe-commits]

mstorsjo wrote:

> Very interesting... See also #68092, now I understand even less what the problem is...

No idea actually, but I tested passing `-Xcc --target=x86_64-w64-mingw32` to an MSVC-built clang-repl, and then it outputs the expected things.

Not sure at what level some JIT deduplication should be happening, but anyway, the MSVC C++ ABI is distinctly different from the Itanium C++ ABI, in most aspects.

https://github.com/llvm/llvm-project/pull/70991