nutdec: improve information in error message

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/nutdec.c

@@ -623,7 +623,7 @@ static int find_and_decode_index(NUTContext *nut)
                 int flag = x & 1;
                 x >>= 1;
                 if (n + x >= syncpoint_count + 1) {
-                    av_log(s, AV_LOG_ERROR, "index overflow A\n");
+                    av_log(s, AV_LOG_ERROR, "index overflow A %d + %d >= %d\n", n, x, syncpoint_count + 1);
                     goto fail;
                 }
                 while (x--)