8048179: Early reclaim of large objects that are referenced by a few objects Summary: Push the remembered sets of large objects with few referenced into the dirty card queue at the beginning of the evacuation so that they may end up with zero remembered set entries at the end of the collection, and are potentially reclaimed. Also improve timing measurements of the early reclaim mechanism, and shorten flag names. Reviewed-by: brutisso, jmasa, dfazunen

8067676: Add applicable closed gc jtreg tests to run in JPRT Reviewed-by: ehelin