RFR [sh/11]: Move Shenandoah clone-expansion from shared code to ShBSC2

[Roman Kennke]

>>> This is a follow-up to recent jdk11u merge. It moves the Shenandoah
>>> clone-expansion code to ShBSC2.
>>>
>>> http://cr.openjdk.java.net/~rkennke/sh11-c2clone/webrev.00/
>>
>> jdk/jdk has clone_needs_barrier in the condition here:
>>
>>   if (ShenandoahCloneBarrier && clone_needs_barrier(src, phase->igvn())) {
>>
>> Does it make sense in sh/jdk11? There is a definition of clone_needs_barrier already, but it is unused.
> 
> Ah, it is probably inlined here. Your call if you still want to do clone_needs_barrier call instead
> (it would clean up some code too).

Right! It's much nicer when using the helper method instead:

http://cr.openjdk.java.net/~rkennke/sh11-c2clone/webrev.01/

Testing still good.

Roman