[glib] Improve documentation for g_strcmp0()

[Christian Dywan <cdywan src gnome org>]

commit b116838da31dc212c60f13821dfe87187731dc78
Author: Milan Bouchet-Valat <nalimilan club fr>
Date:   Wed Jun 23 12:17:29 2010 +0200

    Improve documentation for g_strcmp0()
    
    Be more explicit about the handling of two NULL pointers.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=622480

 glib/gtestutils.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/glib/gtestutils.c b/glib/gtestutils.c
index 3e96465..31a4a5d 100644
--- a/glib/gtestutils.c
+++ b/glib/gtestutils.c
@@ -1429,6 +1429,7 @@ g_assertion_message_error (const char     *domain,
  *
  * Compares @str1 and @str2 like strcmp(). Handles %NULL 
  * gracefully by sorting it before non-%NULL strings.
+ * Comparing two %NULL pointers returns 0.
  *
  * Returns: -1, 0 or 1, if @str1 is <, == or > than @str2.
  *