[vector] Rename reduction test methods

[Paul Sandoz]

Hi,

Please review this patch that renames reduction test methods:

  http://cr.openjdk.java.net/~psandoz/panama/vector-test-rename-reduction-test-methods/webrev/ <http://cr.openjdk.java.net/~psandoz/panama/vector-test-rename-reduction-test-methods/webrev/>

Thanks,
Paul.