protocol: add wl_fixes interface

This commit describes a new wl_fixes interface that can be used to destroy wl_registry objects.

Users of libwayland-client should use it as follows:

• call wl_fixes_destroy_registry(registry)
• call wl_registry_destroy(registry)

Users of libwayland-server should, in their implementation of the request, call wl_resource_destroy(registry).

It should be similar in other protocol implementations.

Signed-off-by: Julian Orth ju.orth@gmail.com

Fixes #461.

Implementations (all draft):

• cosmic: https://github.com/pop-os/cosmic-comp/pull/477
• jay: https://github.com/mahkoh/jay/pull/184
• mesa: mesa/mesa!29140
• smithay: https://github.com/Smithay/smithay/pull/1428
• wayland-rs: https://github.com/Smithay/wayland-rs/pull/726
• wlroots: wlroots/wlroots!4685