[clang] nonblocking/nonallocating attributes (was: nolock/noalloc) (PR #84983)

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Sirraide wrote:

> I think the code to do this could live in the effect set if it were under Sema (as I just described)

Seeing as the effect set is part of the type, at least the parts that are stored in the `FunctionProtoType` can’t be in Sema and have to stay in the AST library.

https://github.com/llvm/llvm-project/pull/84983