Missing structs due to array size calculations
Causes missing structs in ImageMagick.

```c
struct foo { int foo[8 + 1]; };
```

```lisp
(translation_unit 1 1 31
 (struct_specifier 1 1 30
  (type_identifier 1 8 3)
  (field_declaration_list 1 12 19
   (field_declaration 1 14 15
    (primitive_type 1 14 3)
    (array_declarator 1 18 10
     (field_identifier 1 18 3)
     (math_expression 1 22 5
      (number_literal 1 22 1)
      (number_literal 1 26 1)
     )
    )
   )
  )
 )
)
```
