test: check that an empty argument list is treated as (void)

test/compiler/funcdef.st

@@ -9,7 +9,7 @@ ss simple {
     state simple {
         when () {
             void *p = f1();
-            p = f2(p,0);
+            p = f2(p,(double **)f1a);
             pvSetX(1.0);
         } exit
     }
@@ -20,6 +20,11 @@ void *f1(void)
     return 0;
 }
 
+void *f1a()
+{
+    return 0;
+}
+
 void *f2(void *x, double **d)
 {
     void *(*f)(void) = (void *(*)(void))x;