8147611: G1 - Missing memory barrier in start_cset_region_for_worker

Reviewed-by: mgerdin, tschatzl

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

@@ -2790,6 +2790,7 @@ HeapRegion* G1CollectedHeap::start_cset_region_for_worker(uint worker_i) {
       // Previous workers starting region is valid
       // so let's iterate from there
       start_ind = (cs_size * (worker_i - 1)) / active_workers;
+      OrderAccess::loadload();
       result = _worker_cset_start_region[worker_i - 1];
     }