package/directfb-examples: DirectFB examples package

Add the DirectFB examples package.

This patch adds the DirectFB examples package to Buildroot. It is
largely based on a patch written by Daniel Laird, and available at 
http://bugs.uclibc.org/view.php?id=4224

. I only made a few adaptations 
to get it to work properly.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Daniel Laird <daniel.j.laird@nxp.com>