Actually, are we going too far here?
1) The original problem was that embedding couldn't build (it couldn't
even autoreconf) because of the embedded ltdl. Not because of plugins
being enabled. That's fixed with my patch and with yours.
tests/embedded/ runs fine now.
2) Now, we're disallowing plugins entirely in the embedded case too.
That's kind of orthogonal to (1). I don't think we currently have a
single line of code to support this. If people want plugins and
embedded, thay will need to setup ltdl in their own configure. I don't
see any reason to prevent this. We may have users wanting this one day,
so I think we should remove the current error message.
3) And we're disallowing included ltdl too. I am actually not against
this one. We don't use advanced ltdl features, and I don't plan to
change the plugin management code. So the installed ltdl should be fine.
But now that (1) is fixed, there's no direct reason to do (3) immediately.