Builtins are incorrectly hinted as unhashable

I believe this was partially introduced by #8465. I ran into this issue while looking into microsoft/pyright#5446.

According to the python docs, a type that redefines __eq__ but not __hash__ is unhashable.

In the current typeshed hints, many types explicitly define __eq__ (int for example) but do not define hash. A type checker could incorrectly assume that the type is unhashable because of this.