7068240: G1: Long "parallel other time" and "ext root scanning" when running specific benchmark

In root processing, move the scanning of the reference processor's discovered lists to before RSet updating and scanning. When scanning the reference processor's discovered lists, use a buffering closure so that the time spent copying any reference object is correctly attributed. Also removed a couple of unused and irrelevant timers.

Reviewed-by: ysr, jmasa
4 files changed