strsignal() was standardized in POSIX-2008

ok millert@

src/lib/libc/string/strsignal.3

@@ -29,9 +29,9 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"	$OpenBSD: strsignal.3,v 1.6 2011/07/25 00:38:53 schwarze Exp $
+.\"	$OpenBSD: strsignal.3,v 1.7 2012/03/26 05:06:35 guenther Exp $
 .\"
-.Dd $Mdocdate: July 25 2011 $
+.Dd $Mdocdate: March 26 2012 $
 .Dt STRSIGNAL 3
 .Os
 .Sh NAME
@@ -54,6 +54,11 @@ overwritten by subsequent calls to
 .Xr intro 2 ,
 .Xr psignal 3 ,
 .Xr setlocale 3
+.Sh STANDARDS
+The
+.Fn strsignal
+function conforms to
+.St -p1003.1-2008 .
 .Sh HISTORY
 The
 .Fn strsignal