Added caching patch files for XBMC

Backports two patches for caching from XBMC:

https://github.com/xbmc/xbmc/commit/018fab22495e5de370b1e6b69e37e93657921f89
https://github.com/xbmc/xbmc/commit/c90da1375e57c7b1db0f39353830d08adc9dd6be

Improves cache handling on Raspberry Pi's enourmously.