RFR (XS): 8200730: Fix debug=gc+phases time tracking in Remark and Cleanup

[Thomas Schatzl]

Hi all,

  ping for any reviewer...

Thanks,
  Thomas

On Wed, 2018-04-04 at 14:26 +0200, Thomas Schatzl wrote:
> Hi all,
> 
>   can I have reviews to let the recently introduced timing
> measurements
> in Remark and Cleanup pauses actually show useful numbers?
> 
> The problem is that the GCTraceTime instances were not assigned to a
> variable inside a scope so the compiler immediately destructed it,
> always giving "0.000ms" lengths.
> 
> Also added to use the gc timer to these lines for JFR support.
> 
> I would like to think this is a trivial change.
> 
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8200730
> Webrev:
> http://cr.openjdk.java.net/~tschatzl/8200730/webrev
> Testing:
> manual verification that the shown numbers are sane
> 
> Thanks,
>   Thomas
>