swapchain: Refactor to store age implicitly in list
swapchain: Refactor to store age implicitly in list
Instead of storing the age in each slot with no defined order, instead
put previously used buffer slots in a wl_list where the youngest buffers
are at the head.
This guarantees that the swapchain will return younger buffers if it can.
This does the same thing that !3686 (closed) does but in a much simpler way.
Edited by Alexander Orzechowski