Patch merged into coreboot/master: BuildSystem: Add Memtest86+ as a secondary payload

the following patch was just integrated into master:
commit be63a24c4ce29e7e9f096b9ebd94e6d5a65f24a9
Author: Martin Roth 
Date:   Sun Feb 28 15:56:27 2016 -0800

BuildSystem: Add Memtest86+ as a secondary payload

This allows memtest86+ to be added to CBFS as a 'secondary'
    payload on x86 systems, to be loaded by the main payload
    if desired.

Selecting this option, which defaults to no, builds the memtest86+
    payload and adds it to CBFS as `img/memtest` which can then be
    loaded by for example SeaBIOS or GRUB.

Change-Id: Iecf876aaf588ba1df7abdf6668cb26f089bf5f42
    Signed-off-by: Martin Roth 
    Reviewed-on: https://review.coreboot.org/13858
    Reviewed-by: Patrick Georgi 
    Tested-by: build bot (Jenkins)
    Reviewed-by: Ben Gardner

See https://review.coreboot.org/13858 for details.

-gerrit