LLVM invalid linkage error from nested closures

Code:

``` rust
(||||42)()()
```

Error:

```
Global is external, but doesn't have external or weak linkage!
i32 (%closure*)* @_ZN4main12closure.1067E
invalid linkage type for function declaration
i32 (%closure*)* @_ZN4main12closure.1067E
LLVM ERROR: Broken module found, compilation aborted!
```
