ffi/ffi-swig-generator — pull request #35 by davispuh (2014-11-09 01:23:25+00:00)
Title: Return struct by pointer for callback

When have a callback which returns struct
```c
typedef struct S {
const struct S* (*cb)(const struct S*p);
}
```
it was generated as
```ruby
class S < FFI::Struct
layout(
:cb, callback([ :pointer ], S.by_value)
)
end
```

but it's actually a pointer to struct, not by value.
with this PR it will be
```ruby
class S < FFI::Struct
layout(
:cb, callback([ :pointer ], S.ptr)
)
end
```