xf86drmMode: introduce drmModeConnectorGetPossibleCrtcs
Nowadays, users don't really care about encoders except for retrieving the list of CRTCs compatible with a connector. Introduce a new function so that users no longer need to deal with encoders.
This is a re-do of 1, but with a slightly different API.
Signed-off-by: Simon Ser contact@emersion.fr
@pq, are you happy with this version? It's more painful than the other version for new users, but is better than nothing.