[clang] [compiler-rt] [llvm] [XRay] Add `-fxray-default-options` to pass build-time defined XRay options (PR #116878)

[Min-Yih Hsu via cfe-commits]

mshockwave wrote:

> Perhaps `__xray_default_options()` like `__asan_default_options()`? The user would need to provide a `.o` that defines the function, but there is more flexibility (e.g. the function can inspect a config file).

I think this will be a better idea. It simplifies the design and no longer requires changes in Clang driver and the additional LLVM Pass (i.e. XRayPreparation). I implemented that in #117921 and will close this PR in favor of that one.

https://github.com/llvm/llvm-project/pull/116878