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

Add __FBSDID() tags.

MFC after: 3 days

Eliminate 19 warnings in libc (at level WARNS=2) of the
`implicit declaration of function' variety.

Reflect MAC kernel/user API changes into the libc MAC implementation.
This removes a lot of complexity, since we basically just reserve
space on a retrieval of a label, and pass around strings. Two new
elements: (1) consumers of the API must now declare what label
elements they are interested in retrieving, or (2) rely on the default
provided in a new configuration file, mac.conf.

Approved by: re
Obtained from: TrustedBSD Project
Sponsored by: DARPA, Network Associates Laboratories

Introduce support for Mandatory Access Control and extensible
kernel access control.

Extensions to libc to provide basic MAC label manipulation facilities
for userland. These interface will be replaced in the next month
or two with more flexible interfaces, but provide sufficient support
to allow use of the Biba and MLS policies for user applications.

libc_r wrappers to follow.

Obtained from: TrustedBSD Project
Sponsored by: DARPA, NAI Labs