This is what Windows do as described by AF in bug 10525 (I tested it and
all 3 enumeration functions indeed do catch page faults and fail
gracefully). Should fix bugs 10525 and 16320.
It would be better to use SEH only around the real callback call,
and not around the whole API body. Adding 2 wrappers for calling
the callbacks would simplify the code. And the tests wouldn't hurt.