long was being incorrectly used as an x86-sized register, both for 32 and 64
bits, but this is not the case in win64.
Originally committed as revision 31153 to svn://svn.mplayerhq.hu/mplayer/trunk/libswscale
The old code is correct only when stride = 2*width.
Patch by Ronaldo Moura <ronaldo d moura monity com br>
Originally committed as revision 31142 to svn://svn.mplayerhq.hu/mplayer/trunk/libswscale