Allow in-page links (#) when `:safe_links_only` is set

`with_toc_data` is useless with `safe_links_only` because the latter denies to link to any of the headlines.

```ruby
renderer = Redcarpet::Render::HTML.new({
  safe_links_only: true,
  with_toc_data: true
})
md = Redcarpet::Markdown.new(renderer)
md.render("[link](#head)\n# head")
```

result:
```HTML
<p>[link](#head)</p>

<h1 id="head">head</h1>

```

What I expected was this:
```HTML
<p><a href="#head">link</a></p>

<h1 id=\"head\">head</h1>

```