Don't tolerate EBADF on close. (#2002)
Don't tolerate EBADF on close. (#2002)

Motivation:

It's like that #1999 was a little wide, and we should have forbidden
EBDAF on close.

Modifications:

Still forbid EBADF on close.

Result:

EBADF still preconditions on close.
apple/swift-nio,apple/swift-nio,apple/swift-nio,apple/swift-nio,apple/swift-nio