libnice: new package

libnice: new package

[Thomas:
 - Rename patch to the proper naming convention
 - Reduce patch to only take care of the IPv6 case
 - Add description in the patch
 - Propagate libglib2 dependencies in Config.in + added the
   corresponding comment.
 - Added a real help text, and fixed the help text indentation.
 - Fixed the comment header in the .mk file to have the right number
   of # signs.
 - Added the license informations
 - Added a dependency on host-pkgconf, used by the configure script
 - Added --without-gstreamer and --without-gstreamer-0.10 to be
   explicit about the fact that we don't support GStreamer in libnice
   for now.
 - Fixed the hash file to have the proper format.]

Signed-off-by: Gregory Dymarek <gregd72002@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>