RFR: JDK-8303183: Memory leak in Arguments::init_shared_archive_paths

[Justin King]

Fix memory leak by freeing the memory returned by `Arguments::get_default_shared_archive_path()`.

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Commit messages:
 - Fix memory leak in Arguments::init_shared_archive_paths

Changes: https://git.openjdk.org/jdk/pull/12749/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12749&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303183
  Stats: 4 lines in 1 file changed: 2 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/12749.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12749/head:pull/12749

PR: https://git.openjdk.org/jdk/pull/12749