* Use dirname, don't try to use a shortcut that doesn't always work.
This uses the cheap implementation of dirname from sets.subr.
* Fix error in getopts string ("-p" option takes an arg).
* Explicitly use ${HOST_SH} to run culldeps script, because we might
be on a host where /bin/sh is not a POSIX shell.
Reviewed by agc
2f132c6998