RFR 9: 8152005: sun/misc/SunMiscSignalTest.java failed intermittently

[Roger Riggs]

Please review this improvement to an intermittently failing test of 
sun.misc.Signal.
The timeout value is increased in case of a busy system and for additional
debug value the raising of the signal is retried.

Webrev:
    http://cr.openjdk.java.net/~rriggs/webrev-signal-8152005/

Issue:
   https://bugs.openjdk.java.net/browse/JDK-8152005

Thanks, Roger