ECL crashes on iOS loading ASDF libs with several dependencies

[PR]

Hi,

ECL on iOS seems to run fine so far, but there is an issue when trying
to load ASDF systems which depend on several other ones. The full
description of the issue can be found here (including a backtrace):

https://gitlab.com/eql/eql5-ios/-/issues/3

It would be great if somebody with experience of the ECL internals
could look at this, since it's kind of a show stopper for the (free)
CL REPL app.

Thanks for any hints,

Paul