RFR: Bulk backport to sh/jdk9

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/backports/jdk9-20171009/webrev.01/

Our sh/jdk10 testing seems good with the recent sh/jdk10 changes, so let's backport all of them.

Changes include:

rev 13686 : [backport] Remove ShenandoahGCWorkerPerJavaThread flag
rev 13687 : [backport] Double check for UseShenandoahGC in WB expand
rev 13688 : [backport] Fix conditional store in interpreter matrix barrier
rev 13689 : [backport] Verifier should print verification label at liveness verification
rev 13690 : [backport] Mark bitmap slices commit/uncommit

Testing: hotspot_gc_shenandoah {fastdebug|release}

Thanks,
-Aleksey