AmqpObject.State should be thread safe

[nemakam]

AmqpObject.State currently is a property on the object which is used to to implement methods like IsClosed(). Unless these are thread safe, they might not return the latest value. One of volatile/interlocked/lock should be used for this property.
Similar to Azure/azure-service-bus-dotnet#297

Sample code where this becomes an issue:

while (timeoutHelper.RemainingTime() > TimeSpan.Zero)
{
	IEnumerable<AmqpMessage> amqpMessages = null;
	var hasMessages = await Task.Factory.FromAsync(
		(c, s) => receiveLink.BeginReceiveRemoteMessages(maxMessageCount, DefaultBatchFlushInterval, timeoutHelper.RemainingTime(), c, s),
		a => receiveLink.EndReceiveMessages(a, out amqpMessages),
		this).ConfigureAwait(false);
	Exception exception;
	if ((exception = receiveLink.GetInnerException()) != null)
	{
		throw exception;
	}

	if (receiveLink.IsClosing())
	{
		break;
	}
}

In the above case, receiveLink.IsClosing() will not return true if the link (through linkManager) is closed on a different thread.

[xinchen10]

Receive now throws when the link is closed.