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

[via cfe-commits]

Sirraide 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.

Actually, the named loops implementation proper and this would be more or less orthogonal, so if you want to keep working on this feel free to; if not then I’ll take a look at it after named loops is merged (the only reason I don’t want to make it part of the named loops patch is because I’d have to fix a bunch of otherwise unrelated tests...).

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