* Do not interleave root_directory_as_fd with stdio fields
* Do not use different serialization key for different modes
pointing to same path
* Escape stdio file paths (as per
9be46b1da8)
`c->cpu_sched_reset_on_fork` is serialized using
`exec-context-cpu-sched-reset-on-fork` and
`exec-context-cpu-scheduling-reset-on-fork`. Let's keep only the second one, to
serialize the value only if `cpu_sched_set` is true.
