RFR: 8315942: Sort platform enums and definitions after JDK-8304913 follow-ups

[Aleksey Shipilev]

@RogerRiggs asked for this. The moves are mechanical, so nothing should be lost. Tell me if other things need to be sorted as well.

I would wait a little to see if there are any more JDK-8304913 followups.

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/15640/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15640&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8315942
  Stats: 29 lines in 3 files changed: 12 ins; 11 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/15640.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15640/head:pull/15640

PR: https://git.openjdk.org/jdk/pull/15640