RFR: 8304915: Create jdk.internal.util.Architecture enum and apply [v12]

[Roger Riggs]

> Define an internal jdk.internal.util.Architecture enumeration and static methods to replace uses of the system property `os.arch`.
> The enumeration values are defined to match those used in the build.
> The initial values are: `X64, X86, AARCH64, RISCV64, S390, PPC64`
> Note that `amd64` and `x86_64` in the build are represented by `X64`.
> The value of the system property `os.arch` is unchanged.
> 
> The API is similar to the jdk.internal.util.OperatingSystem enum created by #[12931](https://git.openjdk.org/jdk/pull/12931).
> Uses in `java.base` and a few others are included but other modules will be done in separate PRs.

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

  Correct mapping and test of ppc64

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13357/files
  - new: https://git.openjdk.org/jdk/pull/13357/files/1c0c0220..71135e3b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13357&range=11
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13357&range=10-11

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/13357.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13357/head:pull/13357

PR: https://git.openjdk.org/jdk/pull/13357