[11] 2020-02-27, Bulk backports to sh/jdk11

[Aleksey Shipilev]

https://cr.openjdk.java.net/~shade/shenandoah/backports/jdk11-20200227/webrev.01/

This backports another batch of simple changes:

 [backport] 8238385: CTW: C2 (Shenandoah) compilation fails with "Range check dependent CastII node
was not removed"
 [backport] 8240076: Shenandoah: pacer should cover reset and preclean phases
 [backport] 8240069: Shenandoah: turn more flags diagnostic
 [backport] 8239904: Shenandoah: accumulated penalties should not be over 100% of capacity
 [backport] 8239868: Shenandoah: ditch C2 node limit adjustments
 [backport] 8240070: Shenandoah: remove obsolete ShenandoahCommonGCStateLoads

Testing: hotspot_gc_shenandoah {fastdebug,release}

-- 
Thanks,
-Aleksey