RFR: 8254351: Minimal VM build fails with undeclared identifier 'MaxVectorSize' after JDK-8252847

[Jie Fu]

To fix the bug, #if COMPILER2_OR_JVMCI was added.
Please review it. Thanks.

Testing:
  - Minimal and server-fastdebug builds on x86

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Commit messages:
 - 8254351: Minimal VM build fails with undeclared identifier 'MaxVectorSize' after JDK-8252847

Changes: https://git.openjdk.java.net/jdk/pull/588/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=588&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254351
  Stats: 19 lines in 2 files changed: 18 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/588.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/588/head:pull/588

PR: https://git.openjdk.java.net/jdk/pull/588