Wincache driver support

I'm worried about performance with this- it's going to be iterating through every key in the system each time a clear operation is run, and doing a regular expression on it. One way to optimize this would be to do a stringlength check, followed by a direct comparison between the supplied key and a substr of the key.

Do you know if the ucache_entries are sorted? If they are then you can also stop immediately after a failure follows a success.