Backports to sh/jdk1 2019-03-18

[Roman Kennke]

>> Full webrev:
>> http://cr.openjdk.java.net/~rkennke/backports-jdk11-2019-03-18/webrev.00/
> 
> Looks good.
> 
> *) I checked that +UseTransparentHugePages and +UseLargePages work fine on my examples.
> 
> *) Also diff'ed ShenandoahHeap::initialize with jdk12 version, and there is a teeny-tiny difference
> here:
> 
>   141   size_t init_byte_size = collector_policy()->initial_heap_byte_size();
>   142   size_t max_byte_size = collector_policy()->max_heap_byte_size();
>   143   size_t heap_alignment = collector_policy()->heap_alignment();
> 
> L142 is aligned by "=" in jdk12 and jdk/jdk.
> 
> *) This line should probably be moved from "Figure out heap sizing" block to "Initialize the rest of
> GC subsystems". hotspot_gc_shenandoah has to pass after this move :)
> 
>   152   BarrierSet::set_barrier_set(new ShenandoahBarrierSet(this));

http://cr.openjdk.java.net/~rkennke/backports-jdk11-2019-03-18/webrev.01/

Still passes hotspot_gc_shenandoah.