RFR: 8351313: VM crashes when AOTMode/AOTCache/AOTConfiguration are empty

[Ioi Lam]

Please review this trivial patch. When `-XX:AOTMode=`, etc, is given on the command line, the global takes on the problematic value `nullptr`. I added constraint functions to forbid such cases.

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Commit messages:
 - 8351313: VM crashes when AOTMode/AOTCache/AOTConfiguration are empty

Changes: https://git.openjdk.org/jdk/pull/25078/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25078&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8351313
  Stats: 40 lines in 4 files changed: 39 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/25078.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25078/head:pull/25078

PR: https://git.openjdk.org/jdk/pull/25078