@dillo
Thanks, I got it to compile now (well, once I switched to gmake ;)
I get as far as the "Allow" screen of GoToSocial (https://polymaths.social/oauth/authorize), but clicking on the "Allow" button doesn't do anything. Trying to refresh the page or manually go on to the next page (https://smolfedi.pollux.casa/callback.php) doesn't seem to work, either.
It could just be a GtS issue.
This is what the pertinent snippet of the html of that page looks like:
<div class="page-content">
<main>
<section class="with-form" aria-labelledby="authorize">
<h2 id="authorize">Authorize app</h2>
<form action="/oauth/authorize" method="POST">
<p>Hi <b>rl_dane</b>!</p>
<p>
Application
<b>SmolFedi/smolfedi.pollux.casa</b>
would like to perform actions on your behalf, with scope
<em>read write follow</em>.
</p>
<p>
To continue, the application will redirect to: <code>https://smolfedi.pollux.casa/callback.php</code>
</p>
<button type="submit" class="btn btn-success">Allow</button>
</form>
</section>
</main>
</div>