RFR: 8319559: [JVMCI] ensureLinked must be able to call Java

[Doug Simon]

As of [JDK-8318694](https://bugs.openjdk.org/browse/JDK-8318694), only a few select C2V entry points in `jvmciCompilerToVM.cpp` can make Java calls. The `ensureLinked` method was not included but needs to be as it is called from a Truffle context executing on a Compiler thread.

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Commit messages:
 - ensureLinked must be able to call Java

Changes: https://git.openjdk.org/jdk/pull/16530/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16530&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319559
  Stats: 1 line in 1 file changed: 1 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/16530.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16530/head:pull/16530

PR: https://git.openjdk.org/jdk/pull/16530