package/libcodec2: new package

[Thomas:
 - replace patches from Bernd by patches that are Git formatted and
   have a chance of being upstream.
 - remove the no longer necessary post configure hook to build
   generate_cookbook for the host
 - pass --disable-unittests to disable unit tests.]

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