Merge remote-tracking branch 'remotes/stsquad/tags/pull-ci-updates-210617-2' into...

Merge remote-tracking branch 'remotes/stsquad/tags/pull-ci-updates-210617-2' into staging

This is mostly Philippe's updates

We add the following cross-compile targets:
  - mipsel-softmmu,mipsel-linux-user,mips64el-linux-user
  - armeb-linux-user

While I was rolling I discovered we could also back out a bunch of the
emdebian hacks as the newly released stretch handles cross compilers
as first class citizens. Unfortunately this also meant I had to drop
the powerpc support as that is no longer in Debian stable.

# gpg: Signature made Wed 21 Jun 2017 15:09:50 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-210617-2: (21 commits)
  MAINTAINERS: self-appoint me as reviewer in build/test automation
  MAINTAINERS: add Shippable automation platform URL
  shippable: add mipsel target
  shippable: add armeb-linux-user target
  shippable: be verbose while building docker images
  shippable: do not initialize submodules automatically
  shippable: build using all available cpus
  shippable: use C locale to simplify console output
  docker: add mipsel build target
  docker: add extra libs to s390x target to extend codebase coverage
  docker: add extra libs to arm64 target to extend codebase coverage
  docker: add extra libs to armhf target to extend codebase coverage
  docker: use eatmydata in debian arm64 image
  docker: use eatmydata in debian armhf image
  docker: use eatmydata, install common build packages in base image
  docker: use better regex to generate deb-src entries
  docker: install ca-certificates package in base image
  docker: rebuild image if 'extra files' checksum does not match
  docker: add --include-files argument to 'build' command
  docker: let _copy_with_mkdir() sub_path argument be optional
  ...

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