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)

Fix some more warnings found by clang.

Replace strlen(_PATH_DEV) with sizeof(_PATH_DEV) - 1.

Suggested by: kib
Approved by: kib (mentor)
MFC after: 5 days

- Remove gc_argname field. It was introduced for gpart(8), but if I
understand everything correctly, we don't really need it.
- Provide default numeric value as strings. This allows to simplify
a lot of code.
- Bump version number.

Do not bzero() NULL pointer on malloc() error.

Submitted by: Dmitry Luhtionov

Clean up of dead code and possible unassigned variable usage.

Found by: LLVM/Clang Static Checker
Approved by: gnn (mentor)

Fix signed/unsigned comparison compiler warning.

Bring in the GEOM Virtualisation class, which allows to create huge GEOM
providers with limited physical storage and add physical storage as
needed.

Submitted by: Ivan Voras
Sponsored by: Google Summer of Code 2006
Approved by: re (kensmith)