RFR JDK-8166890: JShell: locks forever when input is piped

[Jan Lahoda]

Hi,

When an input is redirected to jshell, like:
echo "1" | jshell

Then jshell locks, as it waits for the terminal to report the cursor 
position. Also, when the input is fully read, the 
StopDetectingInputStream is set to the CLOSED state, but the state may 
be cleared using setState, causing the readers from the 
StopDetectingInputStream to wait indefinitely.

Bug:
https://bugs.openjdk.java.net/browse/JDK-8166890

Webrevs:
jdk:
http://cr.openjdk.java.net/~jlahoda/8166890/jdk.00/
langtools:
http://cr.openjdk.java.net/~jlahoda/8166890/langtools.00/

Any feedback is welcome.

Thanks,
    Jan