Replace pseudo-LRU approach of determining which buffer
to remove when running out of space allowed for cache
with approach which would remove the frame which is most
far away from newly added frame.
This is still a bit tricky because it's impossible to
distinguish which frame to delete in situation of:
CCCC...CC
^
it's either user wants to extend left segment of cached
frames and buffers from right segment should be removed
or he wants to join this two segments and in that case
buffers from right segment should be removed.
Would need a bit more investigation which situation
is more common in general usecase.
5c70c29b9c