RFR: Refactor concurrent partial shortcut

[Roman Kennke]

Am 10.10.2017 um 17:02 schrieb Aleksey Shipilev:
> http://cr.openjdk.java.net/~shade/shenandoah/concpartial-shortcut/webrev.01/
>
> This rebuilds the has_work shortcut, so it does not mess up with code paths in conc-partial and
> final-partial. It also moves the in_progress=true flag setting to appropriate place, so that we
> don't go out via the shortcut, and have this flag still set.
>
> Testing: hotspot_gc_shenandoah (+ hand tests for shortcut)
>
> Thanks,
> -Aleksey
>
Looks ok. I am currently looking at the bug with C1