small inet_ntop.m4 fix

[Simon Josefsson]

Hi Yoann!  Ok to install this?  Gnulib assumes that sys/types.h
exists, and inet_ntop never tested HAVE_SYS_TYPES_H anyway.

--- inet_ntop.m4        16 Jun 2006 17:35:55 +0200      1.2
+++ inet_ntop.m4        17 Jun 2006 21:01:02 +0200      
@@ -1,5 +1,5 @@
-# inet_ntop.m4 serial 1
-dnl Copyright (C) 2005 Free Software Foundation, Inc.
+# inet_ntop.m4 serial 2
+dnl Copyright (C) 2005, 2006 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -12,7 +12,7 @@
 
 # Prerequisites of lib/inet_ntop.h and lib/inet_ntop.c.
 AC_DEFUN([gl_PREREQ_INET_NTOP], [
-  AC_CHECK_HEADERS_ONCE(sys/types.h arpa/inet.h)
+  AC_CHECK_HEADERS_ONCE(arpa/inet.h)
   AC_CHECK_DECLS([inet_ntop],,,[#include <arpa/inet.h>])
   AC_REQUIRE([gl_SOCKET_FAMILIES])
 ])