Remove a lot of warnings (considered as errors by dune).

Also fix a bug in Lic2soc.make_e2a_elt where some deps and some
actions were lost. Actually, this bug ought to be triggered only with
nested calls. So this affects only programs executed via the
-knc/-keep-nested-calls option. and -2c is not supposed to work in
conjunction with -knc ! Hence this fix does not fix anything. But
still it fixes potentially future code if I (or someone else) decide
to handle nested calls in the lic one day.

is the clock of the quicker clock among its inputs, not among its output !

nb : I've transformed all the regressions I've seen into todo entries
in todo.org.

nb 2 : I did not mv the newly broken tests into the broken dirs. I'll
do that for those I do not want to fix in the short term.