RFR: 8340843: [PPC64] Error: ShouldNotReachHere() in TemplateInterpreterGenerator::generate_math_entry after 8338694

[Martin Doerr]

[JDK-8338694](https://bugs.openjdk.org/browse/JDK-8338694) introduced `Interpreter::java_lang_math_tanh` which needs to be handled by the interpreter. Unfortunately, `SharedRuntime::dtanh` does not exist, so we need to fallback to the normal interpreter entry (as before JDK-8338694).

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Commit messages:
 - 8340843: [PPC64] Error: ShouldNotReachHere() in TemplateInterpreterGenerator::generate_math_entry after 8338694

Changes: https://git.openjdk.org/jdk/pull/21168/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=21168&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8340843
  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/21168.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21168/head:pull/21168

PR: https://git.openjdk.org/jdk/pull/21168