hg: code-tools/jmh: Collections.emptyIterator() is only available in JDK 7.

[aleksey.shipilev at oracle.com]

Changeset: 56852f8f4a8d
Author:    shade
Date:      2013-11-04 11:51 +0100
URL:       http://hg.openjdk.java.net/code-tools/jmh/rev/56852f8f4a8d

Collections.emptyIterator() is only available in JDK 7.
Get the JDK 6 build working again.
(Some time in the future I would stop doing this).

! jmh-core/src/main/java/org/openjdk/jmh/util/internal/MultisetStatistics.java