[8u60] approval request for 8075604: jjs exits even when non-daemon threads are still active

[A. Sundararajan]

Please approve.

Bug: https://bugs.openjdk.java.net/browse/JDK-8075604
jdk9 review thread: 
http://mail.openjdk.java.net/pipermail/nashorn-dev/2015-March/004376.html
jdk8u-dev webrev: http://cr.openjdk.java.net/~sundar/8075604/8u60/webrev.00/

Backported "as is" except for modular source layout difference.

Thanks,
-Sundar