libavcodec/motion-test: set the bitexact flag

this is needed for testing mmx2 functions
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/motion-test.c

@@ -128,6 +128,7 @@ int main(int argc, char **argv)
 
     ctx = avcodec_alloc_context3(NULL);
     ctx->dsp_mask = AV_CPU_FLAG_FORCE;
+    ctx->flags |= CODEC_FLAG_BITEXACT;
     memset(&cctx, 0, sizeof(cctx));
     ff_dsputil_init(&cctx, ctx);
     for (c = 0; c < flags_size; c++) {