WII: Implement changes needed by DevKitPPC R26 and later

This changes makes ScummVM compilable with newer versions of DevKitPPC. ScummVM can be linked against the original libogc and libfat. That makes some newer WiiMotes work, improves audio-/video-playback and contains various improvements.
Merge pull request #413 from AReim1982/master

WII: Implement changes needed by DevKitPPC R26 and later