[PATCH 4/8] compositor: set and use the presentation clock everywhere

From: Pekka Paalanen Add presentation clock setters that verify the given clock actually works. Offer an automatic choice of a software fallback clock, when a backend has to always use clock_gettime() to approximate the presentation time. The DRM backend already queried the DRM about the clock i

[PATCH 4/8] compositor: set and use the presentation clock everywhere

From: Pekka Paalanen Add presentation clock setters that verify the given clock actually works. Offer an automatic choice of a software fallback clock, when a backend has to always use clock_gettime() to approximate the presentation time. The DRM backend already queried the DRM about the clock i