[11] 2020-05-12, Bulk backports to sh/jdk11

[Roman Kennke]

Looks good to me.

Thanks,
Roman

> https://cr.openjdk.java.net/~shade/shenandoah/backports/jdk11-20200512/webrev.01/
> 
> This backports logging improvements to sh/jdk11. Not all patches apply cleanly, so please review
> carefully.
> 
> Changesets:
>  [backport] 8241984: Shenandoah: enhance GCTimer and JFR support
>  [backport] 8242375: Shenandoah: Remove ShenandoahHeuristic::record_gc_start/end methods
>  [backport] 8242400: Shenandoah: Restore logging to pre-jdk8241984 format
>  [backport] 8242625: Shenandoah: restore heap logging for Degenerated/Full cycles
>  [backport] 8242638: Shenandoah: restore heap logging for uncommit
>  [backport] 8243487: Shenandoah: make _num_phases illegal phase type
>  [backport] 8243494: Shenandoah: set counters once per cycle
>  [backport] 8239786: Shenandoah: print per-cycle statistics
>  [backport] 8243848: Shenandoah: Windows build fails after JDK-8239786
>  [backport] 8243573: Shenandoah: rename GCParPhases and related code
>  [backport] 8243578: Shenandoah: Cleanup ShenandoahStringDedup::parallel_oops_do()
>  [backport] 8244180: Shenandoah: carry Phase to ShWorkerTimingsTracker explicitly
>  [backport] 8244226: Shenandoah: per-cycle statistics contain worker data from previous cycles
>  [backport] 8244326: Shenandoah: global statistics should not accept bogus samples
> 
> Testing: hotspot_gc_shenandoah {fastdebug,release}, tier{1,2} with Shenandoah, eyeballing gc logs
>