Status of ABCL Backend

[gwbrown]

Following up to the discussion started here, it sounds like the ABCL backend is currently more or less unmaintained, both in Sly and SLIME (I filed an issue there for the lcons* usage that breaks inspecting strings, and haven't gotten any activity, there's a few other noticeable bugs as well). My fixes are PR'd here. I'll try to submit some of these fixes upstream as well, although SLIME needs a subset of these changes due to their different load order.

I think I understand the ABCL backend well enough to be comfortable volunteering to maintain it. It doesn't look like that will require frequent changes really, and what's there is pretty understandable. I kind of expect a new ABCL release semi-soon to support JDK17 though, but I've had absolutely no contact with the maintainers to support that beyond sort of keeping an eye on the commits; I'll probably try to build it from source soon as it would be nice to be on a supported JDK.