RFR: 8285690: CloneableReference subtest should not throw CloneNotSupportedException

[Kim Barrett]

Please review this fix to test/jdk/java/lang/ref/ReferenceClone.java.  It was
passing if CloneableReference::clone were to throw CloneNotSupportedException.
That should be a failure.

Testing:
Locally (linux-x64) verified test still passes.  Temporarily changed
CloneableReference::clone to throw and verified the expected failure gets
reported, unlike before.

-------------

Commit messages:
 - fail test if CloneableReference throws CloneNotSupportedException

Changes: https://git.openjdk.java.net/jdk/pull/8418/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8418&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8285690
  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8418.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8418/head:pull/8418

PR: https://git.openjdk.java.net/jdk/pull/8418