6718125: SA: jmap prints negative size for MaxNewHeap.

Summary: Fixed printing of negative value for MaxNewHeap.
Reviewed-by: jjh

agent/src/share/classes/sun/jvm/hotspot/tools/HeapSummary.java

@@ -193,9 +193,13 @@ public class HeapSummary extends Tool {
 
    private static final double FACTOR = 1024*1024;
    private void printValMB(String title, long value) {
-      double mb = value / FACTOR;
+      if (value < 0) {
+        System.out.println(alignment + title +   (value >>> 20)  + " MB");
+      } else {
+        double mb = value/FACTOR;
         System.out.println(alignment + title + value + " (" + mb + "MB)");
       }
+   }
 
    private void printValue(String title, long value) {
       System.out.println(alignment + title + value);