Merge branch 'master' into core-updates

derivations: Add #:local-build? parameter for derivations.

* guix/derivations.scm (derivation): Add #:local-build? parameter and
  honor it.
  (build-expression->derivation): Likewise.
* doc/guix.texi (Derivations): Update documentation of these
  procedures.

gnu: fltk: New module

* gnu/packages/fltk.scm: New file
* gnu-system.am: New file fltk.scm

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

gnu: libxft: Propagate input.

* gnu/packages/xorg.scm (libxft): Propagate input libxrender.

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

gnu: ncdu: New module

* gnu/packages/ncdu.scm: New file
* gnu-system.am: New file ncdu.scm

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

gnu: Add Corkscrew 2.0.

* gnu/packages/ssh.scm (corkscrew): New variable.

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

gnu: Add ncdc-1.18.1.

* gnu/packages/dc.scm : New module.
* gnu-system.am (GNU_SYSTEM_MODULES): Add module.

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

profiles: Remove misleading message.

Fixes <http://bugs.gnu.org/16484>.
Reported by Andreas Enge <andreas@enge.fr>.

* guix/profiles.scm (profile-derivation)[builder]: Remove "building
  profile '~a' with ~a packages" message.

doc: More about offloading.

* doc/guix.texi (Daemon Offload Setup): Start with "When desired".  Say
  more on what can go in 'machines.scm', and mention Guile-Avahi.
  (Invoking guix-daemon): Document '--no-build-hook'.
  (Invoking guix build): Add xref to "Daemon Offload Setup".

wget: Upgrade to 1.15.

* gnu/packages/wget.scm (wget): Upgrade to 1.15.  Remove Gettext from
  'inputs'.  Move Perl to 'native-inputs'.

gnu: ffmpeg: Update to 2.1.3.

* gnu/packages/video.scm (ffmpeg): Update to 2.1.3.

gnu: ffmpeg: Add input opus.

* gnu/packages/video.scm (ffmpeg): Add input opus.

Add Sree to 'AUTHORS'.

gnu: Add Opus 1.1.

* gnu/packages/xiph.scm (opus): New variable.

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

Add 'guix offload' as a daemon build hook.

* nix/nix-daemon/guix-daemon.cc (GUIX_OPT_NO_BUILD_HOOK): New macro.
  (options): Add '--no-build-hook'.
  (parse_opt): Handle it.
  (main)[HAVE_DAEMON_OFFLOAD_HOOK]: Set 'useBuildHook' by default.
  Set $NIX_BUILD_HOOK to our offload hook unless otherwise specified.
  [!HAVE_DAEMON_OFFLOAD_HOOK]: Clear 'useBuildHook'.
* pre-inst-env.in: Set and export NIX_BUILD_HOOK.
* nix/scripts/offload.in, guix/scripts/offload.scm: New files.
* guix/ui.scm (show-guix-help)[internal?]: Add "offload".
* config-daemon.ac: Call 'GUIX_CHECK_UNBUFFERED_CBIP'.
  Instantiate 'nix/scripts/offload'.  Set 'BUILD_DAEMON_OFFLOAD'
  conditional, and optionally define 'HAVE_DEAMON_OFFLOAD_HOOK' cpp
  macro.
* daemon.am (nodist_pkglibexec_SCRIPTS)[BUILD_DAEMON_OFFLOAD]: Add it.
* Makefile.am (MODULES)[BUILD_DAEMON_OFFLOAD]: Add
  'guix/scripts/offload.scm'.
  (EXTRA_DIST)[!BUILD_DAEMON_OFFLOAD]: Likewise.
* m4/guix.m4 (GUIX_CHECK_UNBUFFERED_CBIP): New macro.
* doc/guix.texi (Setting Up the Daemon): Move most of the body to...
  (Build Environment Setup): ... this.  New subsection.
  (Daemon Offload Setup): New subsection.

store: Add 'topologically-sorted'.

* guix/store.scm (topologically-sorted): New procedure.
* tests/store.scm ("topologically-sorted, one item",
  "topologically-sorted, several items", "topologically-sorted, more
  difficult"): New tests.

nar: Add 'restore-file-set', for use by build hooks.

* guix/nar.scm (&nar-invalid-hash-error, &nar-signature-error): New
  condition types.
  (&nar-error): Add 'file' and 'port' fields.
  (&nar-read-error): Remove 'port' and 'file' fields.
  (lock-store-file, unlock-store-file, finalize-store-file,
  temporary-store-directory, restore-file-set): New procedures.
* tests/nar.scm (%seed): New variable.
  (random-text): New procedure.
  ("restore-file-set (signed, valid)", "restore-file-set (missing
  signature)", "restore-file-set (corrupt)"): New tests.
* po/Makevars (XGETTEXT_OPTIONS): Add '--keyword=message'.nar fixes
* po/POTFILES.in: Add guix/nar.scm.

store: Add 'with-store' convenience macro.

* guix/store.scm (with-store): New macro.

hash: Add 'open-sha256-input-port', for Guile > 2.0.9.

* guix/hash.scm (open-sha256-input-port): New procedure.
* tests/hash.scm (supports-unbuffered-cbip?): New procedure.
  ("open-sha256-input-port, empty", "open-sha256-input-port, hello",
  "open-sha256-input-port, hello, one two",
  "open-sha256-input-port, hello, read from wrapped port"): New tests.

pki: Factorize signature manipulation procedures.

* guix/pki.scm (signature-subject, signature-signed-data,
  valid-signature?): New procedures.
* guix/scripts/authenticate.scm (guix-authenticate): Adjust to use
  them.