Merge branch 'master' into staging

gnu: iw: Update to 4.9.

* gnu/packages/linux.scm (iw): Update to 4.9.

gnu: pciutils: Update to 3.5.2.

* gnu/packages/pciutils.scm (pciutils): Update to 3.5.2.

tests: Create a copy-on-write image instead of copying eagerly.

* gnu/tests/install.scm (qemu-command/writable-image): Invoke 'qemu-img
-o backing_file' instead of calling 'copy-file'.

gnu: hdf5: Update to 1.8.18 [fixes CVE-2016-{4330,4331,4332,4333}].

* gnu/packages/maths.scm (hdf5): Update to 1.8.18.
[source]: Add alternate URL.

services: nginx: Join strings with spaces.

* gnu/services/web.scm (config-domain-strings, config-index-strings):
Use "string-join" to join strings with spaces.

gnu: gcj: Conditionally apply patch for armhf.

* gnu/packages/gcc.scm (gcj)[source]: Inherit from "gcc" package.
[native-inputs]: Conditionally add arm-patch.
[arguments]: Conditionally add phase "apply-arm-patch".

gnu: borg: Fix the test suite.

* gnu/packages/backup.scm (borg)[arguments]: Use
add-installed-pythonpath and disable tests related to FUSE.

gnu: git: Update to 2.11.0.

* gnu/packages/version-control.scm (git): Update to 2.11.0.

services: Add 'cuirass-service'.

* gnu/services/cuirass.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.
* doc/guix.texi (Continuous integration): New node.

gnu: Add Cuirass.

* gnu/packages/ci.scm (cuirass): New variable.

Co-authored-by: Jan Nieuwenhuizen <janneke@gnu.org>

gnu: guix-0.11.0: Add guile-ssh to inputs.

* gnu/packages/package-management.scm (guile-ssh)[inputs]: Add
  guile-ssh.
  [arguments]: Add guile-ssh to GUILE_LOAD_PATH.

gnu: frescobaldi: Disable tests.

* gnu/packages/music.scm (frescobaldi)[arguments]: Disable tests.

gnu: Add zzuf

* gnu/packages/debug.scm (zzuf): New variable.

gnu: libxi: Update to 1.7.8.

* gnu/packages/xorg.scm (libxi): Update to 1.7.8.

gnu: libxfont: Update to 1.5.2.

* gnu/packages/xorg.scm (libxfont): Update to 1.5.2.

gnu: gphoto2, libgphoto2: Use libjpeg-turbo.

* gnu/packages/photo.scm (gphoto2, libgphoto2)[inputs]: Add libjpeg-turbo.

gnu: spice: Use libjpeg-turbo instead of libjpeg.

* gnu/packages/spice.scm (spice)[inputs]: Use libjpeg-turbo as suggested
during the build.

gnu: icecat: Use libjpeg-turbo instead of bundled libjpeg.

* gnu/packages/gnuzilla.scm (icecat)[source]: Remove bundled libjpeg, which
is actually libjpeg-turbo.
[inputs]: Add libjpeg-turbo.
[arguments]: Use it.

gnu: Add libjpeg-turbo.

* gnu/packages/image.scm (libjpeg-turbo): New variable.