RFR: (sh/jdk11): Move has_object_fields() from shared to shenandoah

[Roman Kennke]

>> http://cr.openjdk.java.net/~rkennke/shjdk11-hasobjfields/webrev.01/
> 
> jdk/jdk has a simpler implementation for has_object_fields():
> 
> bool ciInstanceKlass::has_object_fields() const {
>    GUARDED_VM_ENTRY(
>        return get_instanceKlass()->nonstatic_oop_map_size() > 0;
>      );
> }
> 
> Can we use that instead?

That is even better. Unfortunately, we can't do that in ShBSC2, but I 
guess it's ok.

http://cr.openjdk.java.net/~rkennke/shjdk11-hasobjfields/webrev.02/

What do you think?

Roman