[tests] update oracle

Since this test is supposed to check the order in which globals are presented
after AST reordering, such oracle changes must be considered carefully. Here,
there's no dependency between `j` and `k`, so that they can indeed be swapped.
This in fact better reflect the original global list before reordering

NB: `l` is always at the very top of the list, despite being inserted last. This
might warrant investigation at some point. However, the resulting AST after
reordering is correct, which is the main goal.

tests/syntax/oracle/reorder.res.oracle

@@ -30,10 +30,10 @@ void g(void);
 /*@ logic ℤ l= 1;
  */
 int x;
-/*@ logic ℤ k= l;
- */
 /*@ logic ℤ j= l;
  */
+/*@ logic ℤ k= l;
+ */
 /*@ logic ℤ i= j + k;
  */
 /*@ ensures i ≡ i; */