[glib] gio: Add missing (nullable) annotation

[Philip Withnall <pwithnall src gnome org>]

commit f8ff1049d3e52971813243a559a8148f06c26e15
Author: Philip Withnall <philip withnall collabora co uk>
Date:   Wed Jun 15 11:01:26 2016 -0400

    gio: Add missing (nullable) annotation
    
    Add it to g_application_command_line_get_cwd(). Also add a clarifying
    internal comment about the cwd private member.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=700756

 gio/gapplicationcommandline.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gio/gapplicationcommandline.c b/gio/gapplicationcommandline.c
index 2c67187..c042da0 100644
--- a/gio/gapplicationcommandline.c
+++ b/gio/gapplicationcommandline.c
@@ -230,7 +230,7 @@ struct _GApplicationCommandLinePrivate
   GVariant *arguments;
   GVariant *options;
   GVariantDict *options_dict;
-  gchar *cwd;
+  gchar *cwd;  /* in GLib filename encoding, not UTF-8 */
 
   gchar **environ;
   gint exit_status;
@@ -552,7 +552,7 @@ g_application_command_line_get_stdin (GApplicationCommandLine *cmdline)
  * The return value should not be modified or freed and is valid for as
  * long as @cmdline exists.
  *
- * Returns: (type filename): the current directory, or %NULL
+ * Returns: (nullable) (type filename): the current directory, or %NULL
  *
  * Since: 2.28
  **/