RFR: 8271863: ProblemList serviceability/sa/TestJmapCore.java on linux-x64 with ZGC

[Yasumasa Suenaga]

We saw some failures of TestJmapCore.java, and we need more time to fix it. So we should add it to ProblemList-zgc.

-------------

Commit messages:
 - 8271863: ProblemList serviceability/sa/TestJmapCore.java on linux-x64 with ZGC

Changes: https://git.openjdk.java.net/jdk/pull/4994/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4994&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8271863
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4994.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4994/head:pull/4994

PR: https://git.openjdk.java.net/jdk/pull/4994