Previously, for processes launched by doas the unwrapped doas binary preceded the
setuid-wrapped doas binary in PATH.
This caused error `doas: not installed setuid` when running doas from
processes launched by doas.
doas seems to short-circuit the PATH lookup when called like
`doas -u myuser doas -u myuser ...` so the error doesn't appear in this case.
I recently tried to give myself passwordless `doas` for `virsh` commands
(starting, stopping, and editing VMs), but `doas` was complaining that
it didn't know what `virsh` was.
This patch adds `/run/current-system/sw/{s,}bin` and `/run/wrappers/bin`
to the safe path, allowing system binaries to be discovered and executed
properly.
