ProbModelChecker: Fix reference leak when doing steady-state computation (MTBDD)

We have to clear the StateValues vector of the initial distribution
to avoid a reference leak when using the MTBDD engine. E.g., when
doing

prism prism-examples/dice/dice.pm -ss -mtbdd



git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@11060 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/src/prism/ProbModelChecker.java

@@ -1981,6 +1981,8 @@ public class ProbModelChecker extends NonProbModelChecker
 				JDD.Deref(notInBSCCs);
 			if (solnProbs != null)
 				solnProbs.clear();
+			if (initDist != null)
+				initDist.clear();
 			throw e;
 		}
 
@@ -1993,6 +1995,8 @@ public class ProbModelChecker extends NonProbModelChecker
 		}
 		if (start != notInBSCCs)
 			JDD.Deref(notInBSCCs);
+		if (initDist != null)
+			initDist.clear();
 
 		return solnProbs;
 	}