RFC (L): Merge jdk8u

[Aleksey Shipilev]

Hi,

Our early adopters use shenandoah-jdk8u binary builds for testing.

It is time to merge the upstream updates to shenandoah-jdk8u. It seems that we
are better off pulling the changes from the integration forest [1], where Andrew
had put the most recent 8u131. But we can redo the merge from another repo too,
just tell me which one.

Patch for hotspot repo:
  http://cr.openjdk.java.net/~shade/shenandoah/jdk8u-merge-2017-04.patch

- Couldn't generate a proper webrev for this merge :/
- Notice new tags pulled with the merge.
- Other repos merged without a hitch.

Testing: hotspot_gc_shenandoah, jcstress -m quick

Thanks,
-Aleksey

[1] http://hg.openjdk.java.net/aarch64-port/jdk8u-shenandoah/