combined struct / typedef
From readline.h:

```
typedef struct undo_list {
  struct undo_list *next;
  int start, end;               /* Where the change took place. */
  char *text;                   /* The text to insert, if undoing a delete. */
} UNDO_LIST;
```

is translated to:

```
type
  UNDO_LIST* {.importc: "UNDO_LIST", header: headert, bycopy.} = object
    next*: ptr undo_list
    start*: cint
    `end`*: cint
    text*: cstring
```

``UNDO_LIST`` != ``undo_list``