[clang] [clang][Sema] Fix the continue and break scope for while loops (PR #152606)

[Oliver Hunt via cfe-commits]

ojhunt wrote:

 > I was going to implement this approach as part of my named loops implementation, but adding a scope flag requires changing the underlying type of `ScopeFlags` to `uint64_t` at this point (because we already have 32 scope flags..., so I thought it’d be better to make that a separate patch.

@Sirraide If you're doing a much larger and more important change (zomg, labeled continue and break!!!!) I'm going to close this PR as it seems silly to fix this once, and then replace it.

https://github.com/llvm/llvm-project/pull/152606