RFR: 8319817: Charset constructor should make defensive copy of aliases

[Naoto Sato]

Fixing `Charset(String, String[])` to make a defensive copy of the given `aliases` when necessary.

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Commit messages:
 - Minor fix to test
 - Used convenient method in VM
 - check done early, trusted passes skipped
 - initial commit

Changes: https://git.openjdk.org/jdk/pull/16715/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16715&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8319817
  Stats: 76 lines in 2 files changed: 74 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/16715.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16715/head:pull/16715

PR: https://git.openjdk.org/jdk/pull/16715