RFR(XS): 8161279 - Various JMX-tests timed out

[Dmitrij Pochepko]

Hi,

please review small fix for 8161279 - Various JMX-tests timed out

3 jmx codecache tests timeout on "unpredictable" code heap. This fix 
adds guard to filter such situations using isCodeHeapPredictable method 
in a same manner as in other jmx codecache tests.

webrev: http://cr.openjdk.java.net/~dpochepk/8161279/webrev.01/
CR: https://bugs.openjdk.java.net/browse/JDK-8161279

I've tested this fix on linux-amd64.

Thanks,
Dmitrij