Socket taking 40s to close

[aggarg (Gaurav Aggarwal)]

@blanco-ether

The long close wasn’t a major issue in our application other than it was taking a long time for our user interface to indicate that the server was shut down as it didn’t indicate so until the last FreeRTOS_close was issued.

I think that you can update the UI right after issuing shutdown (which I guess is done in a separate task) and then continue the graceful close sequence.