RFR: 8265403: consolidate definition of CPU features

[Doug Simon]

While porting [JDK-8224974](https://bugs.openjdk.java.net/browse/JDK-8224974) to Graal, I noticed that new CPU features were defined for x86 and AArch64 without being exposed via JVMCI. To avoid this problem in future, this PR updates x86 and AArch64 to define CPU features with a single macro that is used to generate enum declarations as well as vmstructs entries.

In addition, the JVMCI API is updated to exposes the new CPU feature constants and now has a check that ensure these constants are in sync with the underlying macro definition.

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Commit messages:
 - 8265403: consolidate definition of CPU features

Changes: https://git.openjdk.java.net/jdk/pull/3558/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=3558&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8265403
  Stats: 481 lines in 15 files changed: 144 ins; 230 del; 107 mod
  Patch: https://git.openjdk.java.net/jdk/pull/3558.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/3558/head:pull/3558

PR: https://git.openjdk.java.net/jdk/pull/3558