RFR of JDK-8049316: TEST_BUG: java/nio/channels/Selector/Wakeup.java fails in same binary run b19

[Hamlin Li]

Would you please review the below patch?

bug: https://bugs.openjdk.java.net/browse/JDK-8049316
webrev: http://cr.openjdk.java.net/~mli/8049316/webrev.00/

Root cause:
1. it depends on sleeping time to check failure, which is not reliable 
in some extreme situation
2. it mix several tests together with a loop in Sleeper

Solution:
1. synchronize between threads.
2. isolate tests.

Thank you
Hamlin