gnu: Add perl-cgi.

The CGI module was removed from Perl core in v5.21.0.

* gnu/packages/web.scm (perl-cgi): New variable.

gnu: doxygen: Drop propagated input graphviz.

* gnu/packages/doxygen.scm (doxygen)[propagated-inputs]: Drop graphviz.

gnu: doxygen: Update to 1.8.11.

* gnu/packages/doxygen.scm (doxygen)[source]: Update to 1.8.11.
  Drop one patch.
  [build-system]: Switch to cmake-build-system, since gnu-build-system
  is not supported any more.
  [arguments]: Adapt.
  [native-inputs]: Drop unused perl.
* gnu/packages/patches/doxygen-tmake.patch: Remove file.
* gnu/packages/patches/doxygen-test.patch: Adapt.
* gnu-system.am (dist_patch_DATA): Unregister patch.

Merge branch 'master' into core-updates

gnu: Add linux-libre-4.2.5

* gnu/packages/linux.scm (linux-libre-4.2.5): New variable.

gnu: mpv: Update to 0.15.0.

* gnu/packages/video.scm (mpv): Update to 0.15.0.

gnu: magit: Update to 2.4.0.

* gnu/packages/emacs.scm (magit): Update to 2.4.0.

gnu: sxiv: Update to 1.3.2.

* gnu/packages/sxiv.scm (sxiv): Update to 1.3.2.

gnu: manaplus: Update to 1.6.1.16.

* gnu/packages/games.scm (manaplus): Update to 1.6.1.16.

python2-jsonschema: Add python2-functools32 to inputs.

* gnu/packages/python.scm (python2-jsonschema)[inputs]: Add
python2-functools32.
(python2-wheel)[native-inputs]: Specify python2-jsonschema. Add
python2-functools32.
(python2-requests)[propagated-inputs]: Specify python2-wheel.
(python2-ipython)[inputs]: Specify python2-jsonschema, python2-requests.
(python2-rauth)[propagated-inputs]: Specify python2-requests.
* gnu/packages/openstack.scm (python2-requests-mock)[propagated-inputs]:
Specify python2-requests.
(python2-tempest-lib)[propagated-inputs]: Specify python2-jsonschema.
(python2-oslosphinx)[propagated-inputs]: Specify python2-requests.
(python2-keystoneclient)[porpagated-inputs]: Specify python2-requests.
[native-inputs]: Specify python2-oslosphinx, python2-requests-mock,
python2-tempest-lib.
(python2-swiftclient)[propagated-inputs]: Specify python2-requests,
python2-oslosphinx.

gnu: datamash: Update to 1.1.0.

* gnu/packages/datamash.scm (datamash): Update to 1.1.0.

gnu: mariadb: Update to 10.0.23.

* gnu/packages/databases.scm (mariadb): Update to 10.0.23.

gnu: rsync: Update to 3.1.2.

* gnu/packages/rsync.scm (rsync): Update to 3.1.2.

gnu: solfege: Build scores with Lilypond.

* gnu/packages/music.scm (solfege)[inputs]: Add "lilypond".

gnu: bristol: Remove SSE flags on platforms other than x86_64 and i686.

* gnu/packages/music.scm (bristol)[arguments]: Add phase
"remove-sse-flags" to remove unsupported optimizations on platforms
other than x86_64 and i686.

gnu: Add git-annex-remote-hubic.

* gnu/packages/version-control.scm (git-annex-remote-hubic): New variable.

gnu: Add python-urllib3.

* gnu/packages/python.scm (python-urllib3, python2-urllib3): New variables.

gnu: python-wheel: Clarify description.

* gnu/packages/python.scm (python-wheel): Do it.

gnu: python-pytest-cov: Clarify description.

* gnu/packages/python.scm (python-pytest-cov): Do it.

gnu: Add python2-functools32.

* gnu/packages/python.scm (python2-functools32): New variable.