fixes #12899 (#12921)

* fixes #12899

* fixes regression: destroy global variables in reverse declaration order, closureleak test relies on it

tests/gc/closureleak.nim

@@ -6,7 +6,7 @@ discard """
 type
   TFoo* = object
     id: int
-    fn: proc(){.closure.}
+    fn: proc() {.closure.}
 var foo_counter = 0
 var alive_foos = newseq[int](0)
 
@@ -31,7 +31,7 @@ proc newFoo*(): ref TFoo =
   inc foo_counter
 
 for i in 0 ..< 10:
- discard newFoo()
+  discard newFoo()
 
 for i in 0 ..< 10:
   let f = newFoo()