RFR: 8196440: Regression automated Test 'java/awt/TrayIcon/PopupMenuLeakTest/PopupMenuLeakTest.java' fails

[Alexander Zvegintsev]

The test doesn't take into account that SystemTray may not be supported.
In case of Ubuntu this happens when `_NET_SYSTEM_TRAY` is not present.

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Commit messages:
 - initial

Changes: https://git.openjdk.java.net/jdk/pull/6088/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6088&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8196440
  Stats: 6 lines in 2 files changed: 4 ins; 1 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6088.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6088/head:pull/6088

PR: https://git.openjdk.java.net/jdk/pull/6088