RFR: 8202579: Revisit VM_Version and VM_Version_ext for overlap and consolidation [v2]

[Coleen Phillimore]

> This change makes VM_Version_Ext part of VM_Version (the platform dependent part) and moves some duplicated code.  x86 had the most code in VM_Version_Ext, so the most code moved there. There might be some unneeded functions but I didn't want to remove them with this change.
> 
> Tier1 (tier2-4 testing in progress) on linux and windows for x86, aarch64, Oracle platforms and tested builds on:
> linux-aarch64-debug,linux-x86-open,linux-s390x-open,linux-arm32-debug,linux-ppc64le-debug
> and
> linux-x64-zero,linux-x64-zero-debug,linux-x86-zero,linux-x86-zero-debug
> 
> Ran JFR tests manually (it uses os_perf* CPUInformationInterface code).

Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:

  Added an initialization assert.

-------------

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/6820/files
  - new: https://git.openjdk.java.net/jdk/pull/6820/files/e611acb4..569896e9

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=6820&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=6820&range=00-01

  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6820.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6820/head:pull/6820

PR: https://git.openjdk.java.net/jdk/pull/6820