RFR [11] 2018-12-10: Bulk backports to sh/jdk11

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/backports/jdk11-20181210/webrev.01/

This backports recent work to sh/jdk11. It was a quiet half-week, so we have only one thing to
backport, to get Monday backports on track:

[backport] Rename vm_operations_shenandoah.* to shenandoahVMOperations.*

Testing: hotspot_gc_shenandoah {fastdebug|release}

-Aleksey