RFR: 8309727: Assert privileges while reading the jdk.incubator.vector.VECTOR_ACCESS_OOB_CHECK system property

[Chris Hegarty]

A trivial use of the Vector API when run with the security manager and a domain that does not grant permissions fails with java.security.AccessControlException: access denied ("java.util.PropertyPermission" "jdk.incubator.vector.VECTOR_ACCESS_OOB_CHECK" "read").

The fix it minimal, as consistent with other system property access in the JDK - just access the property while asserting privileged. Note: no explicit permission grant to the vector module is required, as it is in the boot loader.

This is the only such security manager related issue I see in this code, and I have looked.

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Commit messages:
 - initial commit

Changes: https://git.openjdk.org/jdk/pull/14392/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14392&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8309727
  Stats: 10 lines in 3 files changed: 7 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/14392.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14392/head:pull/14392

PR: https://git.openjdk.org/jdk/pull/14392