Use __class__.__name__ for boolops lookup

[dbieber]

cmpops, binops, and unops already used this technique, but boolops did not. The reason this technique is preferred to using class for the lookup is that when working with e.g. gast (a cross version compatible AST) the exact type match required by the class lookup fails (since gast.And != ast.And), whereas the name based lookup works fine.

[dbieber]

The failure is in Python 3.6 only self.check_roundtrip('f"{key:4}={value!s}"').

Thoughts on why my change breaks this?

[dbieber]

Rebased.