Romain Vimont authored Dec 17, 2021 and Romain Vimont committed Dec 22, 2021

The deadline computation was shared between the vout thread function and
DisplayPicture(), both by hacking the return value (VLC_EGENERIC meaning
"wait") and using an output parameter, to handle 3 possible cases:
 - VLC_SUCCESS: do not wait
 - VLC_EGENERIC and deadline set: wait for deadline
 - VLC_EGENERIC and deadline not set: wait but no deadline is known

In case of VLC_EGENERIC, the vout thread function computed the max
between the returned value and 100ms.

Simplify by computing the expected deadline from DisplayPicture()
directly.