RFR: ShBS::interpreter_storeval_barrier signature fix and cleanup

[Aleksey Shipilev]

http://cr.openjdk.java.net/~shade/shenandoah/shbs-storeval-fix/webrev.01/

sh/jdk10 aarch64 build fails with:

/pool/buildbot/slaves/sobornost/shenandoah-jdk10/build/src/hotspot/cpu/aarch64/shenandoahBarrierSet_aarch64.cpp:110:6:
error: prototype for ‘void ShenandoahBarrierSet::interpreter_storeval_barrier(MacroAssembler*,
Register)’ does not match any in class ‘ShenandoahBarrierSet’
 void ShenandoahBarrierSet::interpreter_storeval_barrier(MacroAssembler* masm, Register dst) {
      ^~~~~~~~~~~~~~~~~~~~

/pool/buildbot/slaves/sobornost/shenandoah-jdk10/build/src/hotspot/share/gc/shenandoah/shenandoahBarrierSet.hpp:129:8:
error: candidate is: virtual void
ShenandoahBarrierSet::interpreter_storeval_barrier(MacroAssembler*, Register, Register, Register)
   void interpreter_storeval_barrier(MacroAssembler* masm, Register dst, Register tmp, Register thread);
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

This is because the argument lists for interpreter_storeval_barrier are messed up.

Testing: hotspot_fast_gc_shenandoah, builds on x86_64 and aarch64

Thanks,
-Aleksey