Allow non deterministic behavior.

org.sat4j.core/src/main/java/org/sat4j/minisat/orders/RandomLiteralSelectionStrategy.java

@@ -56,7 +56,9 @@ public final class RandomLiteralSelectionStrategy
     /**
      * @since 2.2
      */
-    public static final Random RAND = new Random(123456789);
+    public static final Random RAND = System
+            .getProperty("NONDETERMINISTIC") == null ? new Random(123456789)
+                    : new Random();
 
     public void assignLiteral(int p) {
     }

org.sat4j.core/src/main/java/org/sat4j/minisat/orders/RandomWalkDecorator.java

@@ -53,7 +53,9 @@ public class RandomWalkDecorator implements IOrder, Serializable {
 
     private double p;
 
-    private static final Random RAND = new Random(123456789);
+    private static final Random RAND = System
+            .getProperty("NONDETERMINISTIC") == null ? new Random(123456789)
+                    : new Random();
     private ILits voc;
     private int nbRandomWalks;