zigzag_direct_noperm doesn't exist, remove declaration

Originally committed as revision 6998 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/i386/mpegvideo_mmx.c

@@ -27,7 +27,6 @@
 #include "../avcodec.h"
 #include "x86_cpu.h"
 
-extern uint8_t zigzag_direct_noperm[64];
 extern uint16_t inv_zigzag_direct16[64];
 
 static const unsigned long long int mm_wabs __attribute__ ((aligned(8))) = 0xffffffffffffffffULL;