RFR: 8156500: deadlock provoked by new stress test com/sun/jdi/OomDebugTest.java

[Kim Barrett]

Mandy asked for some additional comments to make life easier for
future readers.  I've also stopped pretending the description for
waitForReferenceProcessing is javadoc, since this function is private
and only accessible via SharedSecrets or reflection that avoids access
control.

Changes only in the jdk tree:

New webrevs:
full: http://cr.openjdk.java.net/~kbarrett/8156500/jdk.05/
incr: http://cr.openjdk.java.net/~kbarrett/8156500/jdk.05.inc/

Unchanged hotspot webrevs:
full: http://cr.openjdk.java.net/~kbarrett/8156500/hotspot.04/
incr: http://cr.openjdk.java.net/~kbarrett/8156500/hotspot.04.inc/