[jdk17u] RFR: JDK-8273593: [REDO] Warn user when using mac-sign option with usiigned app-image.

[Andy Herrick]

backport from jdk18 to jdk17u

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Commit messages:
 -     JDK-8273593: [REDO] Warn user when using mac-sign option with unsigned app-image.

Changes: https://git.openjdk.java.net/jdk17u/pull/72/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=72&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273593
  Stats: 65 lines in 9 files changed: 46 ins; 11 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/72.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/72/head:pull/72

PR: https://git.openjdk.java.net/jdk17u/pull/72