update to jsr166e, renaming spliterator() in ConcurrentHashMapV8 to avoid compile error on Java 8

Hi Elasticsearch team, while playing with ES build on Java 8 I encountered this issue, a name clash of JDK 8 spliterator() method in java.util.Set and jsr166e ConcurrentHashMapV8 spliterator().

I updated to the latest CVS of jsr166e but the issue did not disappear. So I simply renamed the method to spliteratorV7(). This should allow compilation unless this is fixed in upstream jsr66e.