RFR 7144200: java/lang/management/ClassLoadingMXBean/LoadCounts.java failed with JFR enabled

[Jaroslav Bachorik]

The test captures the number of loaded classes right at the start and 
then checks the diffs when it's finished. However, it seems that there 
might by some async class loading still going on, initiated by JFR.

The patch simply adds a loop to wait for the number of loaded classes to 
settle before continuing. This should prevent the test failing with JFR 
intermittently.

Issue:  https://bugs.openjdk.java.net/browse/JDK-7144200
Webrev: http://cr.openjdk.java.net/~jbachorik/7144200/webrev.00/

Cheers,

-JB-