[libgit2-glib] ggit-diff-line.c: Fix return annotations

[Igor Gnatenko <ignatenko src gnome org>]

commit 5e1e0df43c3c34623d3db8edfa4c4a6d2cc330c0
Author: Brian C. Lane <bcl redhat com>
Date:   Wed Aug 30 16:33:54 2017 -0700

    ggit-diff-line.c: Fix return annotations
    
    Add (nullable) as needed.

 libgit2-glib/ggit-diff-line.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/libgit2-glib/ggit-diff-line.c b/libgit2-glib/ggit-diff-line.c
index d9e0573..5f1a3da 100644
--- a/libgit2-glib/ggit-diff-line.c
+++ b/libgit2-glib/ggit-diff-line.c
@@ -70,7 +70,7 @@ _ggit_diff_line_wrap (const git_diff_line *line,
  * Atomically increments the reference count of @line by one.
  * This function is MT-safe and may be called from any thread.
  *
- * Returns: a #GgitDiffLine.
+ * Returns: (transfer none) (nullable): a #GgitDiffLine or %NULL.
  **/
 GgitDiffLine *
 ggit_diff_line_ref (GgitDiffLine *line)
@@ -195,7 +195,7 @@ ggit_diff_line_get_content (GgitDiffLine *line,
  *
  * Get the content of the diff line as UTF-8 encoded text.
  *
- * Returns: the content in utf-8 encoding.
+ * Returns: (transfer none) (nullable): the content in utf-8 encoding or %NULL.
  *
  **/
 const gchar *