[jdk11u-dev] RFR: 8210481: Remove #ifdef cplusplus from vmTestbase

[Goetz Lindenmaier]

I backport this for parity with 11.0.14-oracle.

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Commit messages:
 - Backport 510336c21088fa08d09fab5fe8aac4ed4f7b62c6

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/647/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=647&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8210481
  Stats: 1639 lines in 404 files changed: 0 ins; 1639 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/647.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/647/head:pull/647

PR: https://git.openjdk.java.net/jdk11u-dev/pull/647