RFR: Update copyrights

[Aleksey Shipilev]

Employed the hand-written script to update copyrights to a consistent form, based on historical
(Mercurial) data. This touches only the files that exist in Shenandoah webrev. The copyright update
Webrev is really large, because it includes entire file contents, so patch is easier to review:
  http://cr.openjdk.java.net/~shade/shenandoah/update-copyrights.patch

Testing: tier1_gc_shenandoah

Thanks,
-Aleksey