Merge remote-tracking branch 'remotes/stsquad/tags/pull-ci-updates-for-softfreeze...

Final CI updates for soft-freeze

Tweaks from Paolo for J=x Travis compiles
Bunch of updated cross-compile targets from Philippe
Additional debug tools in travis image from Me

# gpg: Signature made Tue 18 Jul 2017 11:00:26 BST
# gpg:                using RSA key 0xFBD0DB095A9E2A44
# gpg: Good signature from "Alex Bennée (Master Work Key) <alex.bennee@linaro.org>"
# Primary key fingerprint: 6685 AE99 E751 67BC AFC8  DF35 FBD0 DB09 5A9E 2A44

* remotes/stsquad/tags/pull-ci-updates-for-softfreeze-180717-2: (32 commits)
  docker: install clang since Shippable setup_ve() verify it is available
  docker: warn users to use newer debian8/debian9 base image
  docker: add debian Ports base image
  shippable: add win32/64 targets
  docker: add MXE (M cross environment) base image for MinGW-w64
  shippable: add mips64el targets
  docker: add debian/mips64el image
  shippable: use debian/mips[eb] targets
  docker: add debian/mips[eb] images
  shippable: add powerpc target
  docker: add debian/powerpc based on Jessie
  docker: add 'apt-fake' script which generate fake debian packages
  docker: add qemu:debian-jessie based on outdated jessie release
  shippable: add x86_64 targets
  shippable: add ppc64el targets
  shippable: add armel targets
  docker: enable nettle to extend code coverage on arm64
  docker: enable gcrypt to extend code coverage on amd64
  docker: enable netmap to extend code coverage on amd64
  docker: enable virgl to extend code coverage on amd64
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>