RFR: 8079565: aarch64: Add vectorization support for aarch64

[Roland Westrelin]

> http://cr.openjdk.java.net/~enevill/8079565/webrev.00/

The platform specific changes look good.
I don’t have an opinion on these:

-      if (TraceSuperWord && Verbose) {
+      if (TraceSuperWord) {

I never used TraceSuperWord. If someone has opinion, it’s time to speak up I guess.

Roland.