stubtest: fix false-positive error for Protocol __init__s and Protocol __annotations__

[AlexWaygood]

Fixes #12820

[hauntsaninja]

Should this check whether runtime.__init__ is Protocol.__init__? E.g., given python/cpython#31628

[AlexWaygood]

Should this check whether runtime.__init__ is Protocol.__init__? E.g., given python/cpython#31628

I sank some time into this, but I think it might be more trouble than it's worth. The check would be much more complicated than a simple runtime.__init__ is Protocol.__init__ check, due to the fact that there's some pretty cursed stuff going on at runtime with Protocol __init__ methods: https://github.com/python/cpython/blob/3f738600f623b88bc90ec12587f75babb6f1025e/Lib/typing.py#L2086-L2087. The fact that this logic changed in 3.11 to mean that now Protocol __init__s are only sometimes replaced (rather than being replaced all the time) makes it even more complicated.

It's probably doable, but would you accept this patch as-is for now, with a TODO comment saying that we should probably check __init__ in some situations on 3.11+?

[hauntsaninja]

Yup, I'd merge a TODO!

[AlexWaygood]

The output if I run typeshed's stubtest_stdlib.py with this patch applied (on Python 3.10, on my Windows PC):

+note: unused allowlist entry importlib.abc.Traversable.__init__
+note: unused allowlist entry importlib.metadata.PackageMetadata.__init__
+note: unused allowlist entry importlib.metadata._meta.PackageMetadata.__init__
+note: unused allowlist entry importlib.metadata._meta.SimplePath.__init__
+note: unused allowlist entry typing.SupportsAbs.__init__
+note: unused allowlist entry typing.SupportsBytes.__init__
+note: unused allowlist entry typing.SupportsComplex.__init__
+note: unused allowlist entry typing.SupportsFloat.__init__
+note: unused allowlist entry typing.SupportsIndex.__init__
+note: unused allowlist entry typing.SupportsInt.__init__
+note: unused allowlist entry typing.SupportsRound.__init__