we don't compile it in lablgtk3 mode, but that does not mean that it should
not be included in the release.

Allows compiling it regardless of Dgraph availability

Given that the previous commits made so many whitespace changes, it'd be
a shame not to do it

- Fix Value/Value#5
- Fix Value/Value#14

Some case studies (e.g. dyad) use some ugly casts from fd_set_t which lead
to the analysis stopping too early.
Changing the representation of fd_set_t should also help it better conform to
the standard (since a fd_set_t should be able to hold FD_SETSIZE elements).

[Ptests] preserve LOG after STDOPT directive

See merge request frama-c/frama-c!2073

This is absolutely not a sneaky attempt to relaunch a build (now that OCI seems
in better shape) pushing a nearly empty commit.