(URGENT) RFR (8u60) 8080600: AARCH64: testlibrary does not support AArch64

[David Holmes]

This is a partial backport of 8080600 to 8u60 so that the AArch64 
platform is recognized. It is urgent to get in as the door closes on 
8u60 via jdk8u/hs-dev on Thursday night.

The changeset doesn't apply cleanly due to different file names and 
other minor content differences between 9 and 8u.

Original changeset:

http://hg.openjdk.java.net/jdk9/jdk9/hotspot/rev/3f334f56441e

webrev for 8u60:

http://cr.openjdk.java.net/~dholmes/8080600/webrev/

Also I'm dropping the IntrinicsBase part of the patch as it is not 
relevant to 8u at this time and the change would be untestable.

Thanks,
David