RFR: JDK-8311788: ClassLoadUnloadTest fails on AIX after JDK-8193513

[Matthias Baesken]

The change [JDK-8193513](https://bugs.openjdk.org/browse/JDK-8193513) enhanced the test runtime/logging/ClassLoadUnloadTest.java . Unfortunately the test started to fail after this on AIX :

----------System.err:(16/744)----------
 stdout: [];
 stderr: []
 exitValue = 0

java.lang.RuntimeException: '[class,load,cause]' missing from stdout/stderr
at jdk.test.lib.process.OutputAnalyzer.shouldContain(OutputAnalyzer.java:221)
at ClassLoadUnloadTest.checkFor(ClassLoadUnloadTest.java:64)
at ClassLoadUnloadTest.main(ClassLoadUnloadTest.java:128)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
at java.base/java.lang.reflect.Method.invoke(Method.java:580)
at com.sun.javatest.regtest.agent.MainActionHelper$AgentVMRunnable.run(MainActionHelper.java:333)
at java.base/java.lang.Thread.run(Thread.java:1570)


Reason is that we check for class java.lang.StringCoding  in the UL output; but on AIX this class is not loaded because we have a different encoding/charset  (see  ISO_8859_1.INSTANCE in the String class). This different encoding is not using StringCoding.

I suppose the same might be true for JVMs without COMPACT_STRING supported (but did not check in detail) .

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Commit messages:
 - JDK-8311788

Changes: https://git.openjdk.org/jdk/pull/14829/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14829&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8311788
  Stats: 12 lines in 1 file changed: 0 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/14829.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14829/head:pull/14829

PR: https://git.openjdk.org/jdk/pull/14829