RFR: 8304913: Use OperatingSystem, Architecture, and Version in jlink [v4]

[Roger Riggs]

> Refactor the Platform class of jlink to use jdk.internal.util OperatingSystem and Architecture instead of os.name and os.arch. 
> They are direct replacements for the Platform enums except for UNKNOWN; its use is refactored to report errors via exceptions.
> 
> Neither os.name nor os.arch should be assumed to be changeable; 
> one test case is removed because it assumes os.name can be changed on the command line.

Roger Riggs has updated the pull request incrementally with one additional commit since the last revision:

  Correct Platform.is64Bit() to report address size of the architecture enum, not the running system

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13585/files
  - new: https://git.openjdk.org/jdk/pull/13585/files/cfc404c1..db56d702

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13585&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13585&range=02-03

  Stats: 5 lines in 1 file changed: 1 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/13585.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13585/head:pull/13585

PR: https://git.openjdk.org/jdk/pull/13585