MPC Video Decoder: The "Read AR from stream" option was sometimes not working correctly.
MPEG2 Video Decoder: The "Read AR from stream" option was sometimes not working correctly.
Fix compilation after fe65610d8367d1ff614d941d02f5e0710239e47f.

Last minute changes are bad... Also rename Sample Aspect Ratio to Pixel Aspect Ratio to avoid possible confusions.