Note: wl_registry_add_listener is undocumented everywhere. Its implementation calls wl_proxy_add_listener which returns 0 on success or -1 on failure.
Signed-off-by: Ophestra <cat@gensokyo.uk>
These packages are highly specific to hakurei and are difficult to use safely from other pieces of code.
Their exported symbols are made available until v0.4.0 where they will be removed for #24.
Signed-off-by: Ophestra <cat@gensokyo.uk>