to prevent from accidentally loading ./module.kmod when we actually wanted to
load module from the system module area.
To load a module from a filesystem path, the module name must contain at
least on path separator character (/), to load a module from the system
module areas, the name must not contain a path separator character:
modload ./mymod.kmod # loads mymod.kmod from the curren directory
modload mymod # loads mymod.kmod from the system module area
and the metadata required to interpret it. Callers of namei must now
create a pathbuf and pass it to NDINIT (instead of a string and a
uio_seg), then destroy the pathbuf after the namei session is
complete.
Update all namei call sites accordingly. Add a pathbuf(9) man page and
update namei(9).
The pathbuf interface also now appears in a couple of related
additional places that were passing string/uio_seg pairs that were
later fed into NDINIT. Update other call sites accordingly.
