RFR: 8306006: strace001.java fails due to unknown methods on stack

[Fredrik Bredberg]

Added the missing java.lang.Thread.beforeSleep and java.lang.afterSleep to expectedSystemTrace.
Tested on my local machine.

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Commit messages:
 - 8306006: strace001.java fails due to unknown methods on stack

Changes: https://git.openjdk.org/jdk/pull/13476/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=13476&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8306006
  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13476.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13476/head:pull/13476

PR: https://git.openjdk.org/jdk/pull/13476