Don't provide promises when we don't care about results. (#437)
Don't provide promises when we don't care about results. (#437)

Motivation:

When we don't care about the result of an operation, we shouldn't provide
a promise.

While I'm here I also removed an unnecessary close() call in the
AcceptHandler: the close() would be called again almost immediately.

Modifications:

Removed a close() call.
Set `promise: nil` on a pair of close() calls.

Result:

Fewer promise allocations.
apple/swift-nio,apple/swift-nio,apple/swift-nio,apple/swift-nio,apple/swift-nio