[11u] RFR: 8257436: [aarch64] Regressions in ArrayCopyUnalignedDst.testByte/testChar for 65-78 bytes when UseSIMDForMemoryOps is on

[Hohensee, Paul]

Please review this backport to 11u. This is the second follow-on backport after 8255351: Add detection for Graviton 2 CPUs. After the first follow-on backport (8257436, review request posted), patch applies cleanly except for a context difference at the end of hunk #1.

JBS: https://bugs.openjdk.java.net/browse/JDK-8257436
Patch: https://github.com/openjdk/jdk/commit/e8363962
Webrev: http://cr.openjdk.java.net/~phh/8257436/webrev.11u.00/

Thanks,
Paul