[aarch64-port-dev ] RFR: Bulk integration of Shenandoah 2018-05-15

[Roman Kennke]

This integrates latest Shenandoah changes from shenandoah/jdk8u
repository. It includes all Shenandoah changes since Oct 2017. It's all
backports from sh/jdk -> sh/jdk10 -> sh/jdk9 -> sh/jdk8u or jdk8u
specific bugfixes. It's all been reviewed, baked and
thoroughly tested upstream.

The integration brings lots of major and minor improvements, bugfixes
and tests.

The list of changesets to be pushed is this:
http://cr.openjdk.java.net/~rkennke/jdk8u-shenandoah-integration-2018-05-15/jdk8u-shenandoah-integration-2018-05-15.txt

The complete webrev is:
http://cr.openjdk.java.net/~rkennke/jdk8u-shenandoah-integration-2018-05-15/webrev.00/

It builds release+fastdebug, and passes all hotspot_gc_shenandoah tests.

I'll tag the forest with:

aarch64-shenandoah-jdk8u172-b11--shenandoah-merge-2018-05-15