This adds the initial dma-buf feedback implementation, following the
changes in the dma-buf protocol extension.

The initial dma-buf feedback implementation gives support to send
default feedback and per-surface feedback. For now the per-surface
feedback support is very basic and is still not implemented in the
DRM-backend, what basically means that KMS plane's formats/modifiers are
not being exposed to clients. In the next commits of this series we add
the DRM-backend implementation.

This patch is based on previous work of Scott Anderson (@ascent).

Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>
Signed-off-by: Scott Anderson <scott.anderson@collabora.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>