RFR: 8354969: Add strdup function for ResourceArea [v6]

[Anton Artemov]

> Added a strdup() method, as requested by the bug reporter. The method is added to Arena, but also available in ResourceArea, as requested. A test for the method is provided. 
> 
> Testing: tiers 1-4 on multiple platforms.

Anton Artemov has updated the pull request incrementally with one additional commit since the last revision:

  8354969: Addressed reviewers comment.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/24998/files
  - new: https://git.openjdk.org/jdk/pull/24998/files/fb64830a..e65548d5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24998&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24998&range=04-05

  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/24998.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24998/head:pull/24998

PR: https://git.openjdk.org/jdk/pull/24998