RFR of JDK9 8162519: Remove ParallelPrefix.java from ProblemList.txt

[Hamlin Li]

There are 2 issues related to test/java/util/Arrays/ParallelPrefix.java,

  1. JDK-8080165, which is marked as samebinary-highfrequency. Based on 
below information, I think this bug should have been resolved, although 
I don't know which change set resolve the issue,

1. the last failure happened more than one year before;
2. run 3 loops concurrently, in every loop run ParallelPrefix 1000 times 
sequentially, PrefixBug(Paul's reproducible code above) is run in below 
mode on jdk9-b128:
   java -server -XX:LoopUnrollLimit=0 -XX:TieredStopAtLevel=4 PrefixBug
   java -server -XX:LoopUnrollLimit=0 PrefixBug
   java -server PrefixBug
3. issue easily reproduced by build/run "javac/java PrefixBug" on jdk9-b64.

  2. JDK-8085982, which is not reproduced.

So, I think ParallelPrefix.java should be removed from ProblemList.txt

bug: https://bugs.openjdk.java.net/browse/JDK-8162519
webrev: http://cr.openjdk.java.net/~mli/8162519/webrev.00/

Thank you
-Hamlin