Sometimes, C structs contain a trailing variable-length array:

```
struct foo {
    int length;
    char name[]; // size is 'length'
};
```

If we give this to jextract we obtain the attached declaration. There are few issues with it:

* the static allocate methods just allocate a "bare" struct with no space for the array. Instead the allocate methods could accept the length of the trailing array, and allocate enough space for the struct + array

* there is no getter/setter for the variable-length array elements. These can be added easily - if the supplied segment is too small, an out of bound error will occur.

These changes could make working with VLAs a bit easier.