RFR: 8292681: Add JMH for ProtectionDomain

[Eric Caspole]

Add a JMH for ProtectionDomain related to current work on JDK-8292375. Also, add the InMemoryJavaCompiler to the JMH jar, to generate the classes needed for this test and will be useful for future class loading JMH too.

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Commit messages:
 - 8292681: Add JMH for ProtectionDomain

Changes: https://git.openjdk.org/jdk/pull/9950/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9950&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8292681
  Stats: 129 lines in 2 files changed: 128 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/9950.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9950/head:pull/9950

PR: https://git.openjdk.org/jdk/pull/9950