Merge remote-tracking branch 'remotes/stsquad/tags/pull-travis-20160621-1' into staging

This pull request contains:

  - disable sparse testing
  - add trusty build target
  - add libnfs-dev for NFS block driver

These are the same patches posted last week for any last minute review.

# gpg: Signature made Tue 21 Jun 2016 10:06:34 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-travis-20160621-1:
  .travis.yml: disable Sparse testing
  .travis.yml: add trusty GCE target
  .travis.yml: add libnfs-dev for NFS block driver
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

.travis.yml

@@ -17,6 +17,7 @@ addons:
       - libgtk-3-dev
       - libiscsi-dev
       - liblttng-ust-dev
+      - libnfs-dev
       - libncurses5-dev
       - libnss3-dev
       - libpixman-1-dev
@@ -63,9 +64,6 @@ script:
   - make -j3 && ${TEST_CMD}
 matrix:
   include:
-    # Sparse is GCC only
-    - env: CONFIG="--enable-sparse"
-      compiler: gcc
     # gprof/gcov are GCC features
     - env: CONFIG="--enable-gprof --enable-gcov --disable-pie"
       compiler: gcc
@@ -88,3 +86,13 @@ matrix:
     - env: CONFIG=""
       os: osx
       compiler: clang
+    - env: CONFIG=""
+      sudo: required
+      addons:
+      dist: trusty
+      compiler: gcc
+      before_install:
+        - sudo apt-get update -qq
+        - sudo apt-get build-dep -qq qemu
+        - wget -O - http://people.linaro.org/~alex.bennee/qemu-submodule-git-seed.tar.xz | tar -xvJ
+        - git submodule update --init --recursive