[clang] Revert "[Clang] __has_builtin should return false for aux triple builtins (#121839) (PR #124626)

[Joseph Huber via cfe-commits]

https://github.com/jhuber6 approved this pull request.

Honestly I'm wondering if this can only be solved with another preprocessor macro that's like "Can this be used, no I mean it." just for these weird offloading language cases.

https://github.com/llvm/llvm-project/pull/124626