gnu: Add GeoClue desktop service.

* gnu/services/desktop.scm (bool): New top-level helper.
  (upower-configuration-file): Use top-level `bool'.
  (geoclue-application): New public function.
  (%standard-geoclue-applications): New public variable.
  (geoclue-service): New public variable.
  (%desktop-services): Add GeoClue.  Add a comment about activation.
* doc/guix.texi (Desktop Services): Document the GeoClue service.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

Revert "PRELIMINARY: dbus-service: Include system-services directories."

This reverts commit e3484421cb159968fc6fb54f044f84bccfc555e8.

Revert "PRELIMINARY: Modify dbus-configuration to find setuid helper."

This reverts commit fe1f2c80a170feee3e448277b9361092328d355c.

PRELIMINARY: Modify dbus-configuration to find setuid helper.

PRELIMINARY: dbus-service: Include system-services directories.

syscalls: Rename 'network-interfaces' and 'all-network-interfaces'.

* guix/build/syscalls.scm (network-interfaces): Rename to...
  (network-interface-names): ... this.
  (all-network-interfaces): Rename to...
  (all-network-interface-names): ... this.
* gnu/services/networking.scm (dhcp-client-service): Adjust accordingly.
* tests/syscalls.scm ("all-network-interfaces"): Rename to...
  ("all-network-interface-names"): ... this, and adjust accordingly.
  ("network-interfaces"): Rename to...
  ("network-interface-names"): ... this, and adjust accordingly.

Merge branch 'master' into core-updates

system: Use the CRDA udev rules.

* gnu/services/base.scm (%base-services): Add CRDA to the #:rules of
  'udev-service'.
* gnu/system/install.scm (installation-services): Likewise.

system: Make /dev/kvm 660.

* gnu/services/base.scm (kvm-udev-rule): Change /dev/kvm mode to 0660 as a
  followup to the resolution of <http://bugs.gnu.org/18994>.

Merge branch 'master' into core-updates

services: Remove lsh service from %DESKTOP-SERVICES.

Suggested by Mark H Weaver and others
at <http://lists.gnu.org/archive/html/guix-devel/2015-06/msg00227.html>.

* gnu/services/desktop.scm (%desktop-services): Remove call to 'lsh-service'.
* doc/guix.texi (Desktop Services): Adjust accordingly.

Merge branch 'master' into core-updates

Merge branch 'master' into gtk-rebuild

Conflicts:
	gnu/packages/gtk.scm

services: swap: Use 'restart-on-EINTR'.

* gnu/services/base.scm (swap-service)[start, stop]: Use 'restart-on-EINTR'.
* guix/build/syscalls.scm (swapoff): Fix typo in 'throw' arguments.

services: xorg: Add xf86-input-libinput to the server's module path.

* gnu/services/xorg.scm (xorg-configuration-file): Add XF86-INPUT-LIBINPUT.

services: xorg: Assume STARTX is a regular value.

* gnu/services/xorg.scm (slim-service): Expect STARTX to be a regular value,
  not a monadic value.

services: xorg: Allow extra config text to be added verbatim.

* gnu/services/xorg.scm (xorg-configuration-file): Add #:extra-config and
  honor it.
* doc/guix.texi (X Window): Adjust accordingly.

services: xorg: Make 'xorg-configuration-file' public.

* gnu/services/xorg.scm (xorg-configuration-file): New procedure, with code
  formerly in 'xorg-start-command'.
  (xorg-start-command): Remove #:drivers and #:resolutions; add
  #:configuration-file; use it as well as 'xorg-configuration-file'.

services: dhcp-client: Turn up the interfaces before calling 'dhclient'.

Somehow, as of Linux 4.0.2, the interfaces are down by default, which
prevents 'dhclient' from actually using them.

* gnu/services/networking.scm (dhcp-client-service): Call
  'set-network-interface-up' on each item of IFACES.

services: dhcp-client: Better track dhclient's PID.

* gnu/services/networking.scm (dhcp-client-service)[start]: Remove
  PID-FILE first.  When 'call-with-input-file' throws ENOENT, try
  again.