Make DECLARE_ALIGNED_8 align to 8 bytes, never to 16
The DECLARE_ALIGNED_8 macro is defined to align to 16 bytes instead
the 8 suggested by the name on some CPUs. None of the uses of this
macro ever need 16-byte alignment, cases which once did having been
changed to always specify 16 bytes explicitly.
Originally committed as revision 19737 to svn://svn.ffmpeg.org/ffmpeg/trunk