Incorrect Call AST

``` nimrod
import macros

macro def(x: stmt): stmt {.immediate.} =
  echo treeRepr(x)

def name(a, b:cint) => nil
```

Outputs:

```
Infix
  Ident !"=>"
  Call
    Ident !"name"
    Ident !"a"
    Ident !"cint"
  NilLit nil
```

The `b` ident is lost.
