[aarch64-port-dev ] RFR: RFR: Bulk integration shenandoah/jdk8u -> aarch64-port/jdk8u-shenandoah 2018-12-13

[Roman Kennke]

Please review the following proposed changes:

This integrates changes from shenandoah/jdk8u into
aarch64-port/jdk8u-shenandoah repository, reaching back to September 2018.
It's bugfixes, improvements and new features that have been originally
done in Shenandoah dev repo, and then backported to Shenandoah JDK8u
repo and tested there for a while too.

List of changes:
http://cr.openjdk.java.net/~rkennke/jdk8u-shenandoah-integration-2018-12-13/jdk8u-shenandoah-integration-2018-12-13.txt

Webrev showing only shared-changes:
http://cr.openjdk.java.net/~rkennke/jdk8u-shenandoah-integration-2018-12-13/webrev-shared-only.00/

Full webrev:
http://cr.openjdk.java.net/~rkennke/jdk8u-shenandoah-integration-2018-12-13/webrev-all.00/

Thanks,
Roman