[glib] gstrfuncs: Mention nullability in g_ascii_strcasecmp() documentation

[Philip Withnall <pwithnall src gnome org>]

commit cb889d95804144c86d9a64aeb6b21a18df035b7e
Author: Philip Withnall <philip withnall collabora co uk>
Date:   Thu Nov 14 18:06:32 2013 +0000

    gstrfuncs: Mention nullability in g_ascii_strcasecmp() documentation
    
    Like strcmp(), g_ascii_strcasecmp() requires that both of its parameters
    be non-%NULL.

 glib/gstrfuncs.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)
---
diff --git a/glib/gstrfuncs.c b/glib/gstrfuncs.c
index 0925f3d..ad4132d 100644
--- a/glib/gstrfuncs.c
+++ b/glib/gstrfuncs.c
@@ -1761,6 +1761,8 @@ g_ascii_xdigit_value (gchar c)
  * characters include all ASCII letters. If you compare two CP932
  * strings using this function, you will get false matches.
  *
+ * Both @s1 and @s2 must be non-%NULL.
+ *
  * Return value: 0 if the strings match, a negative value if @s1 &lt; @s2,
  *   or a positive value if @s1 &gt; @s2.
  **/