Patch merged into coreboot/master: util/docker: Update docker files for coreboot-sdk & jenkins builders

the following patch was just integrated into master:
commit 2d97cb1be50acdf7e7604dd666d52cb9765de018
Author: Martin Roth 
Date:   Mon May 16 11:27:56 2016 -0600

util/docker: Update docker files for coreboot-sdk & jenkins builders

- Check out the specific toolchain version we want before building
    the toolchain (This version uses 1.42).
    - Add additional libraries and tools needed to build coreboot related
    packages.
    - Move everything required to build any of the coreboot or related
    packages into the coreboot-sdk from coreboot-jenkins-node Dockerfile.
    - Separate the text of the commands in the Dockerfiles.
    - Use nproc to get the number of processors for building the toolchain
    - Add some additional comments about why things are done the way that
    they are to the README
    - Update the version of coreboot-sdk that coreboot-jenkins-node uses to
    1.42. (This matches the toolchain version)
    - Move ccache setup from jenkins-node to coreboot-sdk.
    - Update the maintainer.

Change-Id: I293285ef72e3e70259355d924d425fea98ee773d
    Signed-off-by: Martin Roth 
    Reviewed-on: https://review.coreboot.org/16239
    Tested-by: build bot (Jenkins)
    Reviewed-by: Patrick Georgi

See https://review.coreboot.org/16239 for details.

-gerrit