8058475: TestCMSClassUnloadingEnabledHWM.java fails with '.*CMS Initial Mark.*' missing from stdout/stderr
Reviewed-by: mgerdin, tschatzl, brutisso

Summary: Added -XX:+/-ClassUnloadingWithConcurrentMark
Reviewed-by: jmasa, brutisso, mgerdin

8051883: TEST.groups references missing test: gc/class_unloading/TestCMSClassUnloadingDisabledHWM.java
Reviewed-by: brutisso, tschatzl, ehelin, jmasa, dfazunen

Reviewed-by: mgerdin, jwilhelm