Merge branch 'core-updates'

linux-initrd: Adjust VM code and doc to new 'base-initrd' signature.

This fixes regressions introduced in de1c158 ("system: Add support for
boot-time mapped devices.").

* doc/guix.texi (Initial RAM Disk): Adjust example with custom use of
  'base-initrd'.  Document #:mapped-devices parameter of 'base-initrd'.
* gnu/system/vm.scm (system-disk-image, system-qemu-image,
  virtualized-operating-system): Adjust call to 'base-initrd' to new
  signature.

syscalls: Adjust /proc/net/dev parser for old kernels.

* guix/build/syscalls.scm (%interface-line): Remove whitespace in rest
  pattern.  (There's no extra whitespace after the colon with Linux
  2.6.32.)

download: Use the 'SERVER NAME' TLS extension when possible.

Fixes <http://bugs.gnu.org/18526>.
Reported by Mark H. Weaver.

* guix/build/download.scm (tls-wrap): Add 'server' parameter.  Call
  'set-session-server-name!' when (gnutls) defines it.
  (open-connection-for-uri): Adjust 'tls-wrap' call accordingly.

gnu: perl-tk: Build sequentially.

Fixes <http://bugs.gnu.org/18262>.

* gnu/packages/tcl.scm (perl-tk)[arguments]: Add #:parallel-build? #f.

guix package: Use 'profile-generations'.

* guix/scripts/package.scm (guix-package)[process-actions]: Use
  'profile-generations' instead of the equivalent code.

profiles: Add 'profile-generations'.

* guix/profiles.scm (profile-generations): New procedure.

system: Add support for boot-time mapped devices.

* gnu/build/linux-boot.scm (boot-system): Add #:pre-mount parameter and
  honor it.
* gnu/system/linux-initrd.scm (base-initrd): Add #:mapped-devices
  parameter.  Add 'device-mapping-commands' variable, and use it to
  build the #:pre-mount argument of 'boot-system'.
* gnu/system.scm (mapped-device-user,
  operating-system-user-mapped-devices,
  operating-system-boot-mapped-devices): New procedures.
  (device-mapping-services): Use 'operating-system-user-mapped-devices'
  instead of 'operating-system-mapped-devices'.
  (operating-system-initrd-file): Call the initrd with #:mapped-devices.

activation: Ensure existing user accounts have the right settings.

* gnu/build/activation.scm (modify-user, ensure-user): New procedures.
  (activate-users+groups): Systematically call 'ensure-user'.

gnu: valgrind: Update to 3.10.0.

* gnu/packages/valgrind.scm (valgrind): Update to 3.10.0.
* gnu/packages/patches/valgrind-glibc.patch: Remove.
* gnu-system.am (dist_patch_DATA): Adjust accordingly.

gnu: duplicity: Add dependency on util-linux.

* gnu/packages/backup.scm (duplicity)[native-inputs]: Add util-linux.

gnu: ots: Build sequentially.

* gnu/packages/ots.scm (ots)[arguments]: New field.

gnu: Add sound-theme-freedesktop.

Suggested by Federico Beffa <beffa@ieee.org>.

* gnu/packages/libcanberra.scm (sound-theme-freedesktop): New variable.

gnu: libcanberra: Add dependency on PulseAudio and eudev.

* gnu/packages/libcanberra.scm (libcanberra): Add PulseAudio and eudev
  as inputs.

gnu: emacs: Switch to GTK+ 3.

Suggested by Federico Beffa <beffa@ieee.org>.

* gnu/packages/emacs.scm (emacs): Switch to GTK+ 3.

gnu: cyrus-sasl: Build sequentially.

* gnu/packages/cyrus-sasl.scm (cyrus-sasl)[arguments]: Pass
  #:parallel-build?.

offload: Use a total order when sorting available machines.

* guix/scripts/offload.scm (machine-less-loaded?, machine-faster?):
  Remove.
  (machine-power-factor): New procedure.
  (machine-less-loaded-or-faster?): Use it.

offload: Try another machine when the "best" machine is overloaded.

* guix/scripts/offload.scm (choose-build-machine): When BEST is
  overloaded, try the other machines.

linux-boot: Ask fsck for a progress bar.

* gnu/build/file-systems.scm (check-file-system): Pass '-C 0' to FSCK.
  Suggested by Mark H. Weaver.

gnu: guile-charting: Update to 0.2.0.

* gnu/packages/guile.scm (guile-charting): Update to 0.2.0.  Remove
  now-unnecessary cruft from 'snippet'.  Modify 'godir' in Makefile.in.