O_NOFOLLOW on NetBSD

[Bruno Haible]

Gnulib makes use of O_NOFOLLOW in a couple of places. On NetBSD, this definition
(and some others) are only enabled under _NETBSD_SOURCE. See
http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/sys/fcntl.h?rev=1.48&content-type=text/x-cvsweb-markup

How about this patch?


2017-08-14  Bruno Haible  <address@hidden>

        extensions: Enable NetBSD specific extensions.
        * m4/extensions.m4 (AC_USE_SYSTEM_EXTENSIONS): Define _NETBSD_SOURCE.

diff --git a/m4/extensions.m4 b/m4/extensions.m4
index 0c16bb8..2acbe2e 100644
--- a/m4/extensions.m4
+++ b/m4/extensions.m4
@@ -1,4 +1,4 @@
-# serial 16  -*- Autoconf -*-
+# serial 17  -*- Autoconf -*-
 # Enable extensions on systems that normally disable them.
 
 # Copyright (C) 2003, 2006-2017 Free Software Foundation, Inc.
@@ -68,6 +68,10 @@ dnl configure.ac when using autoheader 2.62.
 #ifndef _GNU_SOURCE
 # undef _GNU_SOURCE
 #endif
+/* Enable NetBSD extensions on NetBSD.  */
+#ifndef _NETBSD_SOURCE
+# undef _NETBSD_SOURCE
+#endif
 /* Enable OpenBSD extensions on NetBSD.  */
 #ifndef _OPENBSD_SOURCE
 # undef _OPENBSD_SOURCE