unsupported match_typespec for structs

```elixir
defmodule Foo do
  defstruct [:foo]
  @spec foo(t) :: %Foo{ foo: t } when t: any()

  def foo(t) do
    %Foo{foo: t}
  end
end
```

```
$ mix type
Compiling 1 file (.ex)
❌  Foo.foo/1
   |
   | unsupported match_typespec(map, %Foo{foo: t}, %Foo{foo: any()})
   |
   | at unknown_file:?
```
I believe this should typecheck.