avutil/bprint: Don't use value of AV_BPRINT_SIZE_AUTOMATIC directly

Reviewed-by: Nicolas George <george@nsup.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavutil/bprint.c

@@ -71,7 +71,7 @@ void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max)
     unsigned size_auto = (char *)buf + sizeof(*buf) -
                          buf->reserved_internal_buffer;
 
-    if (size_max == 1)
+    if (size_max == AV_BPRINT_SIZE_AUTOMATIC)
         size_max = size_auto;
     buf->str      = buf->reserved_internal_buffer;
     buf->len      = 0;