Implement a simple register and lookup for function tables. This is
intended for plugins to expose APIs to other plugins.
It has been very hard to arrange a plugin to be able to call into
another plugin without modifying Weston core to explicitly support each
case. This patch fixes that.
The tests all pass.
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Signed-off-by: Giulio Camuffo <giuliocamuffo@gmail.com>
