Merge remote-tracking branch 'remotes/stsquad/tags/pull-testing-fixes-for-3.1-141118...

Testing tweaks:

  - split MacOSX build
  - fix for readdir() failures in check-tcg

# gpg: Signature made Wed 14 Nov 2018 13:08:24 GMT
# gpg:                using RSA key FBD0DB095A9E2A44
# 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-testing-fixes-for-3.1-141118-1:
  tests/tcg/multiarch: fix 32bit linux-test on 64bit host
  .travis.yml: split MacOSX builds and reduce target list

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