RFR: 8277489: Rewrite JAAS UnixLoginModule with FFM

[Weijun Wang]

Rewrite the native calls with FFM.

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Commit messages:
 - no tabs
 - the fix

Changes: https://git.openjdk.org/jdk/pull/28931/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=28931&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8277489
  Stats: 1208 lines in 9 files changed: 1054 ins; 137 del; 17 mod
  Patch: https://git.openjdk.org/jdk/pull/28931.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/28931/head:pull/28931

PR: https://git.openjdk.org/jdk/pull/28931