[libmediaart] extract: Align annotation with documentation

[Jens Georg <jensgeorg src gnome org>]

commit af4cdd09870b0d038800ec2c09ab5a413f654f83
Author: Jens Georg <mail jensge org>
Date:   Tue Nov 11 09:10:58 2014 +0100

    extract: Align annotation with documentation
    
    Documentation says "or NULL" and the code also handles it, but the g-i
    for this was missing.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=739943

 libmediaart/extract.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/libmediaart/extract.c b/libmediaart/extract.c
index a5d4ad2..1169d2c 100644
--- a/libmediaart/extract.c
+++ b/libmediaart/extract.c
@@ -1609,7 +1609,7 @@ process_thread (GTask        *task,
  * @related_file: File related to the media art
  * @buffer: (array length=len)(allow-none): a buffer containing @file data, or %NULL
  * @len: length of @buffer, or 0
- * @mime: MIME type of @buffer, or %NULL
+ * @mime: (allow-none): MIME type of @buffer, or %NULL
  * @artist: (allow-none): The artist name @file or %NULL
  * @title: (allow-none): The title for @file or %NULL
  * @cancellable: (allow-none): optional #GCancellable object, %NULL to