Add STANDARDS section.

It is part of IEEE Std 1003.1-2001 and 2008, both, but there doesn't seem to be
any difference between the two versions, therefore referencing the older standard.

lib/libc/string/strcasecmp.3

@@ -28,9 +28,9 @@
 .\" SUCH DAMAGE.
 .\"
 .\"     from: @(#)strcasecmp.3	8.1 (Berkeley) 6/9/93
-.\"	$NetBSD: strcasecmp.3,v 1.17 2006/10/16 08:48:45 wiz Exp $
+.\"	$NetBSD: strcasecmp.3,v 1.18 2016/07/12 15:45:24 abhinav Exp $
 .\"
-.Dd June 9, 1993
+.Dd July 11, 2016
 .Dt STRCASECMP 3
 .Os
 .Sh NAME
@@ -78,6 +78,13 @@ characters.
 .Xr strcmp 3 ,
 .Xr strcoll 3 ,
 .Xr strxfrm 3
+.Sh STANDARDS
+The
+.Fn strcasecmp
+and
+.Fn strncasecmp
+conform to
+.St -p1003.1-2001 .
 .Sh HISTORY
 The
 .Fn strcasecmp