[glib] g_uri_unescape_string: Mention (allow-none)/%NULL in documentation

[Vadim Rutkovsky <vrutkovsky src gnome org>]

commit 19e20084abb681a74254ad485c64e34b540cdc46
Author: Arnel A. Borja <kyoushuu yahoo com>
Date:   Mon Jun 10 12:37:42 2013 +0800

    g_uri_unescape_string: Mention (allow-none)/%NULL in documentation
    
    https://bugzilla.gnome.org/show_bug.cgi?id=701409

 glib/gurifuncs.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/glib/gurifuncs.c b/glib/gurifuncs.c
index 5a4a719..b2128a2 100644
--- a/glib/gurifuncs.c
+++ b/glib/gurifuncs.c
@@ -139,7 +139,8 @@ g_uri_unescape_segment (const char *escaped_string,
 /**
  * g_uri_unescape_string:
  * @escaped_string: an escaped string to be unescaped.
- * @illegal_characters: an optional string of illegal characters not to be allowed.
+ * @illegal_characters: (allow-none): a string of illegal characters not to be
+ *      allowed, or %NULL.
  * 
  * Unescapes a whole escaped string.
  *