Restore exception compatibility in TcpListener.EndAccept***

[antonfirsov]

#40476 changed EndAcceptSocket and EndAcceptTcpClient to utilize the Task-based Socket.AcceptAsync implementation instead of the APM code path.
This however introduced a breaking change for the exception being thrown when listener.Stop() has been called, closing the underlying socket between the calls to BeginAccept and EndAccept.
According to the old code and the documentation, we should throw ObjectDisposedException here.

Fixes #41585

/cc @geoffkizer

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[geoffkizer]

There could be other cases that cause this exception.

I think we should check explicitly for !_active before changing to ODE. That's what other routines here do.

[antonfirsov]

I'm wondering what are those other cases?

Anyways, I changed the line to catch (SocketException) when (!_active). Want to be equivalent with the old code.

[geoffkizer]

I'm wondering what are those other cases?

Possibly there aren't any. But it seems better to explicitly check _active, rather than just assume this is the only way that exception can happen.

[antonfirsov]

@karelz if we push this (and #41585) out to 6.0, we probably need to document a breaking change for 5.0, just to undo it later.

[antonfirsov]

/azp run runtime-libraries outerloop

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Azure Pipelines successfully started running 1 pipeline(s).

[karelz]

@antonfirsov I didn't suggest any pushing out of 5.0 -- I just used correct milestone for the PR - which is in master and hence goes into 6.0. Once we have it merged, we can start porting it to 5.0 RC2 branch.
We had an email discussion that for 5.0 RC1 is ok to just document it as a known problem.

[antonfirsov]

/azp run runtime

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[wfurt]

LGTM

[antonfirsov]

OuterLoop failures are unrelated: #41530, #40798, #41606, #41531, #41381

[antonfirsov]

/backport to release/5.0-rc2

[github-actions]

Started backporting to release/5.0-rc2: https://github.com/dotnet/runtime/actions/runs/243045182