Merge remote-tracking branch 'remotes/huth-gitlab/tags/m68k-pull-2019-09-07' into...

Add the m68k next-cube machine

# gpg: Signature made Sat 07 Sep 2019 16:32:53 BST
# gpg:                using RSA key 27B88847EEE0250118F3EAB92ED9D774FE702DB5
# gpg:                issuer "huth@tuxfamily.org"
# gpg: Good signature from "Thomas Huth <th.huth@gmx.de>" [full]
# gpg:                 aka "Thomas Huth <thuth@redhat.com>" [full]
# gpg:                 aka "Thomas Huth <huth@tuxfamily.org>" [full]
# gpg:                 aka "Thomas Huth <th.huth@posteo.de>" [unknown]
# Primary key fingerprint: 27B8 8847 EEE0 2501 18F3  EAB9 2ED9 D774 FE70 2DB5

* remotes/huth-gitlab/tags/m68k-pull-2019-09-07:
  .travis.yml: Let the avocado job run the NeXTcube tests
  tests/acceptance: Add test of NeXTcube framebuffer using OCR
  m68k: Add an entry for the NeXTcube machine to the MAINTAINERS file
  m68k: Add serial controller to the NeXTcube machine
  escc: introduce a selector for the register bit
  m68k: Add NeXTcube machine
  m68k: Add NeXTcube keyboard device
  m68k: Add NeXTcube framebuffer device emulation

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