[other] newruntime: add a simple closure iterator test

tests/destructor/tsimpleclosure.nim

@@ -1,7 +1,8 @@
 discard """
   cmd: '''nim c --newruntime $file'''
   output: '''a b
-0 0  alloc/dealloc pairs: 0'''
+70
+2 2  alloc/dealloc pairs: 0'''
 """
 
 import core / allocators
@@ -13,10 +14,17 @@ proc main(): owned(proc()) =
   result = proc() =
     echo a, " ", b
 
+
+proc foo(f: (iterator(): int)) =
+  for i in f(): echo i
+
 proc wrap =
   let p = main()
   p()
 
+  let fIt = iterator(): int = yield 70
+  foo fIt
+
 wrap()
 let (a, d) = allocCounters()
 discard cprintf("%ld %ld  alloc/dealloc pairs: %ld\n", a, d, system.allocs)