RFR(T): 8225022 Put compiler/graalunit/JttThreadsTest.java on ProblemList-graal.txt

[Daniel D. Daugherty]

Greetings,

Trivial change to reduce noise in the JDK13 CI:

$ hg diff
diff -r 5b400b9121d0 test/hotspot/jtreg/ProblemList-graal.txt
--- a/test/hotspot/jtreg/ProblemList-graal.txt Wed May 29 14:07:27 2019 
-0400
+++ b/test/hotspot/jtreg/ProblemList-graal.txt Wed May 29 18:21:39 2019 
-0400
@@ -39,6 +39,7 @@
  compiler/compilercontrol/mixed/RandomCommandsTest.java 8181753 
generic-all

  compiler/graalunit/HotspotJdk9Test.java 8224254 generic-all
+compiler/graalunit/JttThreadsTest.java 8207757 generic-all

  compiler/jvmci/SecurityRestrictionsTest.java 8181837 generic-all

Thanks, in advance, for any questions, comments or suggestions.

Dan