RFR: Remove obsolete and unused reduce-storeval-barrier optimization code

[Aleksey Shipilev]

On 09/16/2017 11:37 AM, Roman Kennke wrote:
> Ok. I fixed one place in library_call.cpp in the cmpxchg intrinsics. Everything else should be ok:
> 
> http://cr.openjdk.java.net/~rkennke/remove-reduce-storeval/webrev.01/

*) I wonder if instead of putting shenandoah_storeval_barrier prior to store_oop_* calls, we are
better putting the barriers calls inside of them? Under UseShenandoahGC flag? Otherwise, I see
missing shenandoah_storeval_barrier in GraphKit::builtin_throw and Parse::expand_multianewarray.

Seems good otherwise.

Thanks,
-Aleksey