RFR 9: 8146671 [TEST BUG] : java/lang/ref/CleanerTest.java required more memory for -UseCompressedOops runs

[Roger Riggs]

Please review an update to a CleanerTest; the 4m limit is not needed
and causes a problem when run with CompressedOops

Webrev:
   http://cr.openjdk.java.net/~rriggs/webrev-cleanertest-8146671/

Issue:
    https://bugs.openjdk.java.net/browse/JDK-8146671

Thanks, Roger