bird: new package

bird: new package

The BIRD project aims to develop a dynamic IP routing daemon with full
support of all modern routing protocols, easy to use configuration
interface and powerful route filtering language

Signed-off-by: Adrien Gallouët <adrien@gallouet.fr>
[Thomas:
 - Do not make ncurses/readline mandatory dependencies, since they are
   not. They are only needed when building the BIRD client. Added a
   Config.in sub-option to enable/disable the client. As part of this,
   added ncurses/readline to <pkg>_DEPENDENCIES.
 - Add a patch to fix the installation when the BIRD client is
   disabled, the patch has been submitted upstream.
 - Added host-flex and host-bison to <pkg>_DEPENDENCIES since
   flex/bison are used during the build process.
 - Add BR2_USE_MMU dependency, the code uses fork()
 - Fix alphabetic ordering in DEVELOPERS file.]
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>