package/leafnode2: New package

[Thomas:
  - Rewrap help text in Config.in
  - Improve cross-compilation patch to not call the 'amiroot' program
    on the host, while it is compiled for the target.
  - Use CONF_OPTS instead of CONF_OPT.
  - Use a pre-build hook rather than re-implementing the BUILD_CMDS
    entirely.
  - Also include COPYING file in license files.
  - License is LGPLv2.1, not LGPLv2.1+: only one file is LGPLv2.1+,
    the rest doesn't have any "or later" specification, so we assume
    it's only LGPLv2.1.]

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>