RFR: 8344336: SM cleanup of java.lang.System, Runtime, String, StackWalker

[Roger Riggs]

Removed use of SecurityManager to check permissions.
Relaxed defensive copying of byte arrays (due to lack of SM)

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Commit messages:
 - 8344336: SM cleanup of java.lang.System, Runtime, String, StackWalker

Changes: https://git.openjdk.org/jdk/pull/22168/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22168&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344336
  Stats: 164 lines in 5 files changed: 0 ins; 159 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/22168.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22168/head:pull/22168

PR: https://git.openjdk.org/jdk/pull/22168