RFC [8u]: Pick up jdk8u171

[Aleksey Shipilev]

Upstream had published 8u171 sources, let's pick them up to sh/jdk8u.

The merges are automatic. Hotspot diff:
  http://cr.openjdk.java.net/~shade/shenandoah/merge-jdk8u171.patch

(I added the patch from here too:
http://mail.openjdk.java.net/pipermail/aarch64-port-dev/2018-April/005629.html)

Testing: hotspot_gc_shenandoah {fastdebug|release}

Thanks,
-Aleksey