8200723: Suppress rs_length and predicted_cards sampling during mixed gcs Summary: Due to the impact of these measurements on pause time, their high difference to other collections during mixed collections, and their non-use during mixed collections, do not use rs_length and predicted_cards measurements done during mixed gc for the predictor. This avoids the young gen sizing after the mixed phase to be negatively affected by mixed collections. Reviewed-by: kbarrett, sjohanss

8154528: Reclaim regions emptied by marking in Remark pause Reviewed-by: shade, sjohanss

8178105: Switch mark bitmaps during Remark Reviewed-by: sjohanss, sangheki

8201315: (se) Allow SelectableChannel.register to be invoked while selection operation is in progress Reviewed-by: bpb