RFR: 2019-08-20, bulk backports to sh/jdk11

[Roman Kennke]

Looks good, thanks!

Roman



> Let me backport these to sh/jdk11, these open up further simplifications for our upstream exposure
> and testing:
> 
>  [backport] 8229350: Shenandoah does not need barriers before CreateEx
>  [backport] 8229865: Use explicit #include debug.hpp for STATIC_ASSERT in
> gc/shenandoah/shenandoahUtils.cpp
>  [backport] 8229707: [TESTBUG] Some Shenandoah tests assume Server VM by default
>  [backport] 8229416: Shenandoah: Demote or remove ShenandoahOptimize*Final optimizations
>  [backport] 8229419: Shenandoah: Cleanup LRB strength selector code
> 
> Webrev:
>   https://cr.openjdk.java.net/~shade/shenandoah/backports/jdk11-20190820/webrev.01/
> 
> Testing: hotspot_gc_shenandoah
>