net: add header Features.hxx

For improved portability of the net library to projects without
autoconf.

src/net/Features.hxx

@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2003-2015 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef NET_FEATURES_HXX
+#define NET_FEATURES_HXX
+
+/* feature macros are defined in config.h, and this header verifies
+   that it has been included earlier */
+#include "check.h"
+
+#endif

src/net/StaticSocketAddress.hxx

@@ -31,6 +31,7 @@
 #define STATIC_SOCKET_ADDRESS_HXX
 
 #include "SocketAddress.hxx"
+#include "Features.hxx"
 #include "Compiler.h"
 
 #include <assert.h>