[8u] RFA for backport of 8181810: PPC64: Leverage extrdi for bitfield extract

[Matthew Brandyberry]

Hi,//
//
Please approve the backport of JDK-8181810 fix to jdk8u.

The JDK10 change applies cleanly.

Bug: https://bugs.openjdk.java.net/browse/JDK-8181810
Changeset: http://hg.openjdk.java.net/jdk10/jdk10/hotspot/rev/f025cf2a4a78
Review Thread: 
http://mail.openjdk.java.net/pipermail/hotspot-dev/2017-June/027247.html

Thanks,
Matt