6866591: G1: print update buffer processing stats more often
Summary: It adds parameter -XX:+G1SummarizeRSetStatsPeriod that causes update buffer processing information to be printed periodically. It also includes two small formatting changes.
Reviewed-by: jmasa, jcoomes, ysr
6864886: G1: rename -XX parameters related to update buffers
Summary: renaming a couple of update buffer-related parameters to make them more understandable and consistent.
Reviewed-by: iveresov, ysr