Fix x86 build with h264dsp disabled

Originally committed as revision 23844 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/x86/h264dsp_mmx.c

@@ -2347,6 +2347,7 @@ void ff_pred8x8_tm_vp8_mmxext      (uint8_t *src, int stride);
 void ff_pred8x8_tm_vp8_sse2        (uint8_t *src, int stride);
 void ff_pred8x8_tm_vp8_ssse3       (uint8_t *src, int stride);
 
+#if CONFIG_H264DSP
 void ff_h264_pred_init_x86(H264PredContext *h, int codec_id)
 {
 #if HAVE_YASM
@@ -2397,3 +2398,4 @@ void ff_h264_pred_init_x86(H264PredContext *h, int codec_id)
     }
 #endif
 }
+#endif