RFR (S): 8151614: Improve logging in concurrent mark code

[Thomas Schatzl]

Hi,

  thanks for your review.

On Thu, 2016-03-10 at 10:32 -0800, sangheon wrote:
> Hi Thomas,
> 
> Looks nice especially for combining logging and trace event.
> Thanks for cleaning up this.
> 
> One minor comment, could you update the copyright in logPrefix.hpp 
> before pushing?

  updated in place.

Thomas