DX7 Subpic: Avoid resetting the static subpicture when possible.

Also use safer locking.
DX9 Subpic: Avoid resetting the static subpic and the subpic pool when possible.

Also use safer locking.
DX9 Subpic: Remove unused code.
Memory subpic: Mark some global variables static and minor cosmetics.
SubPicAllocators: Const correctness and minor cosmetics.
Subpic queues: Cosmetics.

Be less aggressive when invalidating the queue without threading while at it.
SubPic provider: Minor cosmetics.
Subtitle queue: Clearer display of the queue stats.

Show the start and end time of the queue without trying to normalize with current time.
Temporarily disable the subtitle queue for XySubFilter.

It is not used for now and it will need to be updated after the changes to normal queue are done.
Completely reworked subtitle queue.

The new queue should be a bit faster than the older one for a similar number of buffered subpictures. It should also work much better when the number of subpicture is increased.