7199249: TEST_BUG : Add /othervm to Collisions.java @run main with -D definitions

Reviewed-by: alanb

test/java/util/Map/Collisions.java

@@ -25,7 +25,7 @@
  * @test
  * @bug 7126277
  * @run main Collisions -shortrun
- * @run main -Djdk.map.althashing.threshold=0 Collisions -shortrun
+ * @run main/othervm -Djdk.map.althashing.threshold=0 Collisions -shortrun
  * @summary Ensure Maps behave well with lots of hashCode() collisions.
  * @author Mike Duigou
  */