RFR: 8253284: Zero OrderAccess barrier mappings are incorrect

[Aleksey Shipilev]

There are some jcstress failures with AArch64 Zero. It seems because to happen because `orderAccess_linux_zero.hpp`
defaults to compiler-only barriers for most OrderAccess::* calls. We need to defer to the strongest barriers by
default.

The code also needs some rearrangement to make the mappings clear.

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Commit messages:
 - Mirror the same in bsd_zero.hpp
 - 8253284: Zero OrderAccess barrier mappings are incorrect

Changes: https://git.openjdk.java.net/jdk/pull/224/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=224&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8253284
  Stats: 41 lines in 2 files changed: 14 ins; 16 del; 11 mod
  Patch: https://git.openjdk.java.net/jdk/pull/224.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/224/head:pull/224

PR: https://git.openjdk.java.net/jdk/pull/224