[clang] [Driver][BoundsSafety] Add -fexperimental-bounds-safety flag (PR #70480)

[Fangrui Song via cfe-commits]

MaskRay wrote:

> @MaskRay To be clear, the check is now in Driver as you suggested. It's just that the frontend also has some extra checks too. So, you want me to remove the extra checks in the frontend?

Yes, otherwise it's duplicated check.

In addition, I think our convention is to add the option when the feature is ready, rather than add a no-op option, than build functional patches on top of it.


https://github.com/llvm/llvm-project/pull/70480