Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

- Remove --debug option and intentionally undocument -d, which is only
kept for compatibility with 4.4BSD behavior.
- Sync SYNOPSIS with usage().
- Use an alternative way to represent short and long options which have
same semantics.

Reviewed by: gabor

Replace GNU bc/dc with BSDL versions ported from OpenBSD. They have a good
compatibility level with the GNU counterparts and have shown to be mature
enough. For now, the GNU versions aren't removed from the tree, just detached
from the build.

Sponsored by: Google Summer of Code 2008
Portbuild run by: erwin
Approved by: delphij