config-daemon.ac: detect host AR

The problem is seen when we try to use explicit host:

    ./configure --prefix=/usr --localstatedir=/var/lib --host=x86_64-pc-linux-gnu
    make V=1

Before the change:
    ar cru libstore.a nix/libstore/libstore_a-gc.o
After the change:
    x86_64-pc-linux-gnu-ar cru libstore.a

* config-daemon.ac: use AM_PROG_AR to detect host AR

Signed-off-by: Sergei Trofimovich <slyfox@inbox.ru>
Signed-off-by: Ludovic Courtès <ludo@gnu.org>

linux-container: Add comment on exception handling.

* gnu/build/linux-container.scm (run-container): Add note about writing
the exceptions.

linux-container: Do not rely on 'isatty?'.

This avoids problems where 'isatty?' return #t but 'ttyname' fails with
ENOTTY or such.

* gnu/build/linux-container.scm (mount-file-systems): Remove call of
'isatty?'.  Directly call 'ttyname' and catch 'system-error'.

gnu: xonsh: Update to 0.5.3.

* gnu/packages/shell.scm (xonsh): Update to 0.5.3.

gnu: u-boot: Update to 2017.01.

* gnu/packages/u-boot.scm (u-boot): Update to 2017.01.

gnu: u-boot: Use scandir.

* gnu/packages/u-boot.scm (make-u-boot-package): Modify.

gnu: imagemagick: Update to 6.9.7-7.

* gnu/packages/imagemagick.scm (imagemagick): Update to 6.9.7-7.

gnu: wget: Use libidn2.

Suggested by Efraim Flashner <efraim@flashner.co.il>.

Fixes support for internationalized domain names.

* gnu/packages/wget.scm (wget)[inputs]: Replace libidn with libidn2.

gnu: libidn2: Update to 0.16.

* gnu/packages/libidn.scm (libidn2): Update to 0.16.
[inputs]: Add libunistring.

gnu: linux-libre: Update to 4.9.8.

* gnu/packages/linux.scm (%linux-libre-version, %linux-libre-hash)
(linux-libre): Update to 4.9.8.

gnu: linux-libre@4.4: Update to 4.4.47.

* gnu/packages/linux.scm (linux-libre-4.4): Update to 4.4.47.

gnu: youtube-dl: Update to 2017.02.01

* gnu/packages/video.scm (youtube-dl): Update to 2017.02.01.

gnu: Add python-lzo.

* gnu/packages/compression.scm (python-lzo): New variable.

Co-authored-by: Danny Milosavljevic <dannym@scratchpost.org>

gnu: Add python-lz4.

* gnu/packages/compression.scm (python-lz4): New variable.

gnu: xscreensaver: Update license URI.

* gnu/packages/xdisorg.scm (xscreensaver)[license]: Point to current URL.

gnu: redshift: Remove uneeded input.

This is a followup to b4c400a75c9f432820146dfe24fcebdfbc276e4b.

* gnu/packages/xdisorg.scm (redshift): Remove LIBJPEG.

gnu: wget: Update to 1.19.

* gnu/packages/wget.scm (wget): Update to 1.19.
[home-page]: Use HTTPS.

gnu: cddlib: Fix source URI.

* gnu/packages/maths.scm (cddlib)[source]: Update source URI.

file-systems: Remove dependency on (guix store).

(gnu system file-systems) is used on the "build" side since commit
5970e8e248f6327c41c83b86bb2c89be7c3b1b4e.

* gnu/system/file-systems.scm: Remove dependency on (guix store).
(%store-prefix): New procedure.
* tests/file-systems.scm ("does not pull (guix config)"): New test.

activation: Set the right owner for home directories.

This fixes a regression introduced in
ae763b5b0b7d5e7316a3d0efe991fe8ab2261031 whereby home directories and
skeletons would be root-owned.

* gnu/build/activation.scm (copy-account-skeletons): Make 'directory' a
keyword parameter.  Add #:uid and #:gid and honor them.
[set-owner]: New procedure.
(activate-user-home): Add call to 'getpw' and 'chown'.  Pass UID and GID
to 'copy-account-skeletons'.
* gnu/tests/base.scm (run-basic-test)["skeletons in home directories"]:
Test file ownership under HOME.