Handle the file descriptor statedump

Handle the file descriptor statedump

Now the files opened for each process before the trace is recorded are
associated with the corresponding processes, this removes a lot of
unknown file descriptors.

Signed-off-by: Mathieu Bain <mathieu.bain@polymtl.ca>
Signed-off-by: Julien Desfossez <julien.desfossez@efficios.com>