RFR (7xS): 8178148: Log more detailed information about scan rs phase

[Thomas Schatzl]

Hi all,

  unfortunately, for support of some code there is need for one more
public method in the g1gcphasetimes class.

Webrev:
http://cr.openjdk.java.net/~tschatzl/8178148/webrev.1_to_2/ (diff)
http://cr.openjdk.java.net/~tschatzl/8178148/webrev.2/ (full)

Sorry for the issue.

Thanks,
  Thomas