Assign ErrPipeListenerClosed to net.ErrClosed
Assign ErrPipeListenerClosed to net.ErrClosed

This error used to just be a `errors.New` with the text exactly matching
the "use of closed network connection" that you'd get from the Go stdlib.
Now that that error was exported as `net.ErrClosed` in Go 1.16 we should
be able to swap to this safely, and anyone who relied on checking the
string explicitly should still be fine.

Signed-off-by: Daniel Canter <8d0fd95ae71f7e4870b010b10f83a6201b034a65@microsoft.com>

microsoft/go-winio