Viewing Flamegraphs requires some specific Perl modules (e.g. open),
which are not necessarily available even with conf-perl.
Since this feature is optional and cannot be entirely tested via command-line,
removing it for now is a better approach than trying to extensively check that
each dependence is available in the test machine.

- 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.