RFR(S) : 8152636 : TestHasNegatives.java fails after Jigsaw changes were integrated

[Igor Ignatyev]

http://cr.openjdk.java.net/~iignatyev/8152636/webrev.00/
> 46 lines changed: 39 ins; 2 del; 5 mod; 

Hi all,

could you please review this tiny fix which updates TestHasNegatives.java to work in jigsaw-world?
the test needs access to package-private class (j.l.StringCoding), j.l.Helper class is introduced to provide that access. j.l.Helper is built as patch for ‘java.base' module.

testing: locally + w/ -XX:+PrintInlining to check that j.l.StringCoding::hasNegatives is intrinsified
JBS: https://bugs.openjdk.java.net/browse/JDK-8152636

Thanks,
— Igor