avformat/vorbiscomment: Use 64bit int for ff_vorbiscomment_length()

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

libavformat/vorbiscomment.c

@@ -38,9 +38,9 @@ const AVMetadataConv ff_vorbiscomment_metadata_conv[] = {
     { 0 }
 };
 
-int ff_vorbiscomment_length(AVDictionary *m, const char *vendor_string)
+int64_t ff_vorbiscomment_length(AVDictionary *m, const char *vendor_string)
 {
-    int len = 8;
+    int64_t len = 8;
     len += strlen(vendor_string);
     if (m) {
         AVDictionaryEntry *tag = NULL;

libavformat/vorbiscomment.h

@@ -34,7 +34,7 @@
  * For no string, set to an empty string.
  * @return The length in bytes.
  */
-int ff_vorbiscomment_length(AVDictionary *m, const char *vendor_string);
+int64_t ff_vorbiscomment_length(AVDictionary *m, const char *vendor_string);
 
 /**
  * Write a VorbisComment into a buffer. The buffer, p, must have enough