<i18n dev> RFR: 8282819: Deprecate Locale class constructors [v5]

[Naoto Sato]

> Proposing to deprecate the constructors in the `java.util.Locale` class. There is already a factory method and a builder to return singletons, so there is no need to have constructors anymore unless one purposefully wants to create `ill-formed` Locale objects, which is discouraged. We cannot terminally deprecate those constructors for the compatibility to serialized objects created with older JDKs. Please see the draft CSR for more detail.

Naoto Sato has updated the pull request incrementally with one additional commit since the last revision:

  Refined test cases

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/7947/files
  - new: https://git.openjdk.java.net/jdk/pull/7947/files/9d9d3a69..86c7b586

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=7947&range=04
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=7947&range=03-04

  Stats: 9 lines in 1 file changed: 4 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7947.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7947/head:pull/7947

PR: https://git.openjdk.java.net/jdk/pull/7947