8079208: gc/g1/TestLargePageUseForAuxMemory.java fails due to not considering page allocation granularity for setup

The test case needs to use the OS'es allocation granularity to properly determine the boundary values for the test.

Reviewed-by: dfazunen, jmasa, ecaspole

test/lib/sun/hotspot/WhiteBox.java

@@ -83,6 +83,7 @@ public class WhiteBox {
 
   public native int  getHeapOopSize();
   public native int  getVMPageSize();
+  public native long getVMAllocationGranularity();
   public native long getVMLargePageSize();
 
   private native boolean isObjectInOldGen0(Object o);