loop unrolled for stack marking

tests/accept/compile/teval1.nim

@@ -0,0 +1,19 @@
+import macros
+
+proc testProc: string {.compileTime.} =
+  result = ""
+  result = result & ""
+
+when true:
+  macro test(n: stmt): stmt =
+    result = newNimNode(nnkStmtList)
+    echo "#", testProc(), "#"
+  test:
+    "hi"
+
+const
+  x = testProc()
+  
+echo "##", x, "##"
+
+