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

Merge DTC-d75b33af.

This is a split merge because of non-uniform licensing of the DTC package
contents and the way these components will be used in the FreeBSD environment.

The original DTC package is composed of the following two major pieces:

1. sys/contrib/libfdt (BSD [dual] license)
2. contrib/dtc (GPLv2)

The libfdt component is going to be shared in all aspects of the environment:
- /boot/loader
- kernel
- dtc (the device tree compiler proper, userspace tool)

Initial import of the Device Tree Compiler (DTC) package v1.2.0.

Obtained from: git://git.jdl.com/software/dtc.git