opencv: need threads support

Because the opencv_core module needs threads support, just globally
disable the whole opencv package if the toolchain does not offer this
support.

Fixes:
  http://autobuild.buildroot.org/results/8dd/8dd1674674018a931ba09cc5b414c32360e51692/build-end.log

Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
opencv: cleanup depends and comments

Since the opencv package globally depends on BR2_TOOLCHAIN_HAS_THREADS
and BR2_USE_WCHAR, then cleanup these redundant (and useless)
dependencies in the opencv's sub-options.

Signed-off-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
dependencies.sh: stop stray a.out being created for ia32 compiler test

If the grub package is selected it also selects
BR2_HOSTARCH_NEEDS_IA32_COMPILER.  This triggers a test in dependencies.sh
to verify the host compiler can build 32 bit executables.  Currently this
test does not set any output for the compiler which causes a stray a.out
to be create outside the output directory.  This patch sets the compiler
output to /dev/null so no a.out is created but the test is still performed.

Signed-off-by: Martin Bark <martin@barkynet.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
dependencies.sh: cleanup dependencies.sh

Cleanup mixed indents and remove commented lines.

Signed-off-by: Maxime Hadjinlian <maxime.hadjinlian@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
eudev: new package.

eudev is a userspace device management daemon. It is a standalone
version, independent from systemd. It is a fork maintained by Gentoo.

Features:

 - No extra configuration options are available: Gudev is build if
   libglib2 is selected.
 - No dependency on hwdata as the package uses its own hardware
   database (as does systemd).

eudev 1.3 is in sync with systemd v207.

Signed-off-by: Eric Le Bihan <eric.le.bihan.dev@free.fr>
udev: convert to virtual package.

This patch converts udev to a virtual package. For the moment, there is only
one provider for the udev features: eudev.

Packages meant to provide udev-like features must select the symbol
BR2_PACKAGE_HAS_UDEV.

Packages depending on BR2_ROOTFS_DEVICE_CREATION_DYNAMIC_UDEV or
BR2_PACKAGE_UDEV have been converted to use the new symbol.

Signed-off-by: Eric Le Bihan <eric.le.bihan.dev@free.fr>
systemd: bump to v207.

This patch bumps systemd to v207 but also declares it as a provider for the
udev virtual package.

Starting with systemd 183, udev has been merged into
systemd. The udev daemon is now installed as /lib/systemd/systemd-udevd.
This means that /dev management using udev is only available if systemd
is chosen as init system.

When configuring systemd, the following options are available:

- activation of systemd-journal-gatewayd, to access the journal via
  HTTP.
- activation of extra features like journal compression and sealing.

Support for uClibc has also been removed because:

- upstream has no interest in supporting uClibc.
- using a shrinked libc brings no advantage, given the size of all the
  programs included in Systemd. So using glibc does not matter.

Signed-off-by: Eric Le Bihan <eric.le.bihan.dev@free.fr>
manual: update /dev management section.

This patch updates the /dev management section in the manual with information
about eudev, which replaces udev.
board: add elebihan demo-systemd.

New config files are available to build a kernel and file system to showcase
the use of systemd, with QEMU: one for x86 and the other for ARM.

Signed-off-by: Eric Le Bihan <eric.le.bihan.dev@free.fr>
board: add elebihan demo-eudev.

New config files are available to build a kernel and file system to showcase
the use of eudev, with QEMU: one for x86 and the other for ARM.

Signed-off-by: Eric Le Bihan <eric.le.bihan.dev@free.fr>