RFR: 8275052: AArch64: Fix flag handling for MacOS.

[Andrew Haley]

This is more of the fallout from JDK-8273297.
We've noticed that blocks of less than 8kbytes are very slowly encrypted with AES/GCM . This is because of incorrect flag handline in vm_version_bsd_aarch64.cpp. 

Before this patch:


Benchmark            (dataSize)  (keyLength)  (provider)  Mode  Cnt      Score      Error  Units
AESGCMBench.decrypt        8191          256              avgt    6  95821.232 ± 2447.246  ns/op
AESGCMBench.decrypt        8192          256              avgt    6   3653.619 ±   83.432  ns/op


After:


Benchmark            (dataSize)  (keyLength)  (provider)  Mode  Cnt     Score    Error  Units
AESGCMBench.decrypt        8191          256              avgt    6  3371.735 ± 70.204  ns/op
AESGCMBench.decrypt        8192          256              avgt    6  3119.928 ± 80.375  ns/op

-------------

Commit messages:
 - Fix flag handling for MacOS.

Changes: https://git.openjdk.java.net/jdk/pull/5894/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5894&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8275052
  Stats: 16 lines in 2 files changed: 7 ins; 7 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5894.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5894/head:pull/5894

PR: https://git.openjdk.java.net/jdk/pull/5894