Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Remove code duplication by introducing static gctl_param_add() function which
is now used by both gctl_ro_param() and gctl_rw_param().

- Simplify gctl_get_handle() a bit.
- Prefer 'unsigned int' over 'u_int' in userland code.

- Simplify the procedure of retrieving XML-data from the kernel.
- Fix a number of potential memory leaks in libgeom related to doing realloc
without freeing old pointer if things go wrong.
- Fix a number of places in libgeom where malloc and calloc return values
were not checked.
- Check malloc return value and provide sufficient warning messages when XML
parsing fails.

PR: kern/83464
Submitted by: Dan Lukes <dan - at - obluda.cz>
Approved by: kib (mentor)

Add the part of the last commit which cvs appearantly didn't like
the first time.

Collapse the meta arguments into normal arguments, trying to distinguish
just makes our own life harder.

Run a revision on the OAM api.

Use prefix gctl_ systematically.
Add flag with access perms for each argument.
Add ro/rw versions of argument building functions.
General cleanup.

Add marshalling functions for OAM api.