Removing ocaml-4.01?

[Julien Lepiller]

Hi Ben,

During Fosdem we were discussing a security issue affecting ocaml-4.01. 
It seems that the only user of this version of ocaml is pplacer, which 
has been failing to build consistently since quite some time now. Since 
nobody complained, I suppose nobody uses that package and I'd like to 
suggest we remove it, and all of ocaml 4.01 with it, from guix. It will 
still be possible to install older versions of pplacer with inferiors of 
course.

As the original author of these packages, I guess you are the one with 
the most interest in it. Are you still using it? Could you help us fix 
it?

Thank you!