Bug fix in detection of strict clock contraints in props for digital clocks.

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@2211 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/src/pta/DigitalClocks.java

@@ -337,7 +337,7 @@ public class DigitalClocks
 					}
 				}
 			};
-			modulesFile.accept(astt);
+			ast.accept(astt);
 		} catch (PrismLangException e) {
 			return e.getASTElement();
 		}