[jdk11u-dev] RFR: 8285497: Add system property for Java SE specification maintenance version

[Justin Lu]

Please review this change which is a backport of the `java.specification.maintenance.version` system property part of the JSR384 MR2 Reference Implementation.

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Commit messages:
 - 8285497: Add system property for Java SE specification maintenance version

Changes: https://git.openjdk.org/jdk11u-dev/pull/1878/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=1878&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8285497
  Stats: 23 lines in 4 files changed: 20 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/1878.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/1878/head:pull/1878

PR: https://git.openjdk.org/jdk11u-dev/pull/1878