RFC: Pick up jdk-13+19 to sh/jdk

[Roman Kennke]

Yes, please do it!

Roman


> We have not synced up sh/jdk for a while now. Let's pick up to the latest upstream tag, jdk-13+17.
> Merge is trivial, because sh/jdk has no diffs against jdk/jdk, except tags.
> 
> Changesets:
>    http://cr.openjdk.java.net/~shade/shenandoah/merges/jdk-13%2b19/changesets.txt
> 
> Testing: tier1_gc_shenandoah {fastdebug, release}
>