tun-device: Include system headers before our own

On CentOS 6.5 the sys/capability.h header file defines _LINUX_TYPES_H
without actually including that header, preventing its later inclusion
here.

As library.h (via which the capabilities headers are included) is not
actually required in tun_device.[ch], moving the inclusion of tun_device.h
would not strictly be necessary.  But it's probably a good idea to
include our own headers after system headers anyway, for if one of the
recursively included files at a later point includes library.h we'd have
the same problem again.

src/libstrongswan/networking/tun_device.c

@@ -27,9 +27,11 @@
 #include <unistd.h>
 #include <net/if.h>
 
+#if !defined(__APPLE__) && !defined(__linux__) && !defined(HAVE_NET_IF_TUN_H)
+
 #include "tun_device.h"
 
-#if !defined(__APPLE__) && !defined(__linux__) && !defined(HAVE_NET_IF_TUN_H)
+#include <utils/debug.h>
 
 #warning TUN devices are not supported!
 
@@ -52,7 +54,8 @@ tun_device_t *tun_device_create(const char *name_tmpl)
 #include <net/if_tun.h>
 #endif
 
-#include <library.h>
+#include "tun_device.h"
+
 #include <utils/debug.h>
 #include <threading/thread.h>
 

src/libstrongswan/networking/tun_device.h

@@ -23,7 +23,6 @@
 #ifndef TUN_DEVICE_H_
 #define TUN_DEVICE_H_
 
-#include <library.h>
 #include <networking/host.h>
 
 typedef struct tun_device_t tun_device_t;