[14] RFR (S) 8242365: Shenandoah: use uint16_t instead of jushort for liveness cache

[Aleksey Shipilev]

Original fix:
  https://bugs.openjdk.java.net/browse/JDK-8242365
  https://hg.openjdk.java.net/jdk/jdk/rev/9e3539baac38

The patch does not apply cleanly to 14u due to changed context. I had to change some jushort* to
ShenandoahLiveData* by hand. 14u webrev:
  https://cr.openjdk.java.net/~shade/8242365/webrev.14u.01/

Testing: hotspot_gc_shenandoah

-- 
Thanks,
-Aleksey