[aarch64-port-dev ] RFR: Merge Shenandoah jdk8u

[Roman Kennke]

Hi,

This merges in development of Shenandoah from the last ~1 year into the
aarch64-port/jdk8u-shenandoah/hotspot integration repository. It's a
straight hg pull && hg merge of ~200 changesets from
shenandoah/jdk8u/hotspot.

The list of affected changesets is here:
http://cr.openjdk.java.net/~rkennke/jdk8u-shenandoah-integration-merge/merged-changesets.txt
<http://cr.openjdk.java.net/%7Erkennke/jdk8u-shenandoah-integration-merge/merged-changesets.txt>

The complete webrev is this (not very useful, it includes the 'Merge'
changesets, and lots of empty fluff because of that, but I don't see how
webrev can filter those out...)

http://cr.openjdk.java.net/~rkennke/jdk8u-shenandoah-integration-merge/webrev.00/
<http://cr.openjdk.java.net/%7Erkennke/jdk8u-shenandoah-integration-merge/webrev.00/>

Some notes:

- we backported everything from shenandoah/jdk9, both should be almost
100% the same, except for some internal-APIs changes from 8 to 9

- including Shenandoah specific jtreg tests (which all pass)

- we did plenty of testing both x86 and aarch64. everything looks good
to us. Things tested: jtreg tests, specjvm, specjbb, jcstress, radargun,
jboss eap with specjenterprise

- changes are all Shenandoah-specific. there is some stuff in changed
dirs but this is for Shenandoah specific stuff too (mostly runtime,
interpreter, c1 and c2 barrier related, plus argument handling, etc).

- The merge did not create any conflicts

Good to go?