LICENSES: add the BSD 3-clause "New" or "Revised" License

LICENSES: add the BSD 3-clause "New" or "Revised" License

Add the full text of the BSD 3-clause "New" or "Revised" License to
OpenOCD tree. It was copied directly from:

  https://spdx.org/licenses/BSD-3-Clause.html#licenseText

Add the required tags for reference and tooling.

Change-Id: I0e7977ed92af9d58a4a72152dd792045b237f2f0
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/5971
Tested-by: jenkins