strtonum does not require limits.h

spotted by ray some time ago

src/lib/libc/stdlib/strtonum.3

@@ -1,4 +1,4 @@
-.\" $OpenBSD: strtonum.3,v 1.12 2005/10/26 11:37:58 jmc Exp $
+.\" $OpenBSD: strtonum.3,v 1.13 2006/04/25 05:15:42 tedu Exp $
 .\"
 .\" Copyright (c) 2004 Ted Unangst
 .\"
@@ -22,7 +22,6 @@
 .Nd "reliably convert string value to an integer"
 .Sh SYNOPSIS
 .Fd #include <stdlib.h>
-.Fd #include <limits.h>
 .Ft long long
 .Fo strtonum
 .Fa "const char *nptr"