RFR : exclude tests from jacoco coverage report

[Doug Simon]

Looks good - I’ll integrate it.

> On Mar 11, 2015, at 11:34 AM, Igor Ignatyev <igor.ignatyev at oracle.com> wrote:
> 
> Hi all,
> 
> please review the tiny fix.
> 
> problem:
> tests are excluded from jacoco instrumentation, but they are in reports. that causes incorrect overall percentages.
> 
> fix:
> exclude jtt and all test directories from a report.
> 
> http://cr.openjdk.java.net/~iignatyev/graal/jacocoreport_exclude_test/webrev.00/
> -- 
> Igor