package/swupdate: new package

package/swupdate: new package

swupdate provides a reliable way to update the software on an embedded system.

Note that swupdates has a reworked Kbuild/Kconfig system. It has now support
for the 'option' and 'env' symbols as well for the 'savedefconfig' target.
This makes dependency handling much easier. We're now able to pass which
dependencies are available through the environment, as suggested by Arnout
Vandecappelle [1].

In previous version of this patch we had a configuration setting where all
package dependencies except Lua were selected by default. This has changed with
v7 as we are now able to pass dependencies to the swupdate build system through
the environment. For useful operation swupdate requires a parser which depends
by default on libconfig, but can be replaced by a json-c or Lua parser.

To provide a reasonable firmware update system we enable the embedded webserver
based on mongoose (also see notes about mongoose below), a parser as stated
above and a handler for raw NAND or NOR flash.

The user can modify this configuration by selecting the appropriate dependencies
before running `make swupdate-menuconfig`. The help text contains information
about which packages may be of interest for the user.

The embedded web server requires a website for proper operation. We install the
included website by default, however the user may choose to install a custom
website on the post-build scripts.

Note, swupdate includes some old versions of mongoose and lsqlite3:
  - mongoose is version 3.8 from year 2013
  - lsqlite3 is version 0.8 from year 2011

Currently, swupdate does not provide a way to replace these with external
packages.

This patch is based on a WIP version submitted by Romain Naour, commented by
Arnout Vandecappelle [2].

[1]
http://lists.busybox.net/pipermail/buildroot/2015-March/122981.html

[2]
https://patchwork.ozlabs.org/patch/401270/

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Cc: Romain Naour <romain.naour@openwide.fr>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Arnout Vandecappelle <arnout@mind.be>
Cc: Yann E. MORIN <yann.morin.1998@free.fr>
Tested-by: Mike Williams <mike@mikebwilliams.com>
Reviewed-by: Romain Naour <romain.naour@openwide.fr>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>