update mmx code to latest snow changes

note, the code likely can overflow and thus needs some more changes
sse2 updated too but disabled as it is untested

Originally committed as revision 10223 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/i386/dsputil_mmx.c

@@ -3621,8 +3621,7 @@ void dsputil_init_mmx(DSPContext* c, AVCodecContext *avctx)
 #endif
 
 #ifdef CONFIG_SNOW_DECODER
-#if 0
-        if(mm_flags & MM_SSE2){
+        if(mm_flags & MM_SSE2 & 0){
             c->horizontal_compose97i = ff_snow_horizontal_compose97i_sse2;
             c->vertical_compose97i = ff_snow_vertical_compose97i_sse2;
             c->inner_add_yblock = ff_snow_inner_add_yblock_sse2;
@@ -3632,7 +3631,6 @@ void dsputil_init_mmx(DSPContext* c, AVCodecContext *avctx)
             c->vertical_compose97i = ff_snow_vertical_compose97i_mmx;
             c->inner_add_yblock = ff_snow_inner_add_yblock_mmx;
         }
-#endif
 #endif
 
         if(mm_flags & MM_3DNOW){