RFR(XS): Minor cleanup on ShenandoahHeapRegion's LiveData counter

[Zhengyu Gu]

Shenandoah heap region's LiveData counters are set and cleared by VM thread, so no atomic operations are need.

However, getLiveData() can read the counters updated by increase_live_data() method, so load_acquire() is needed.


Webrev:http://cr.openjdk.java.net/~zgu/cleanup_1/webrev/ 
<http://cr.openjdk.java.net/%7Ezgu/cleanup_1/webrev/>

Thanks,

-Zhengyu