Correct determination of file size and frames in VBRI headers

The fields "Number of Bytes" and "Number of Frames" are mixed up. "Bytes"
come first, "Frames" behind.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 5d305c9398)

libavformat/mp3dec.c

@@ -109,8 +109,8 @@ static int mp3_parse_vbr_tags(AVFormatContext *s, AVStream *st, int64_t base)
         if(avio_rb16(s->pb) == 1) {
             /* skip delay and quality */
             avio_skip(s->pb, 4);
-            frames = avio_rb32(s->pb);
             size = avio_rb32(s->pb);
+            frames = avio_rb32(s->pb);
         }
     }