dev/vndvar.h or dev/ccdvar.h so that struct pool is always available
regardless of multiple inclusion. Actually, ccdconfig.c compiles without
this change but ...
- Refer vnode disk as vnd0 instaed of vnd0c.
- Rename argument to specify vnode disk from special_file to vnode_disk.
- Explain that vnode_disk is a special file or name like vnd0.
- Add one example which uses vnd0 instead of /dev/vnd0c.
- Back to use `rdev' which the name of raw partition, since now opendisk(3)
initializes `buf' except in very trivial case (it is `buf' is NULL).
- Use `rdev' instead of `dev' in verbose output.
- Output `rdev' when warn ioctl failure.
- Use `dev' instead of `rdev' to warn, since latter may not initialized.
- Don't use device file name as a format of warn(). Instead, pass "%s"
explicitly.
- Add optional "geomspec" argument as third argument when configuring
a vnode disk. Format is: secsize/secpertrack/trackpercyl/ncylinders,
e.g. 512/18/2/80.
- Add optional "-t typename" argument, mutually exclusive with "geomspec",
that will look up "typename" in /etc/disktab and use the geometry
specified in the entry.
- Update verbose output accordingly.
