radius: make radius.h self-contained

We need to include "list.h" to define 'struct list_head' and
<netinet/in.h> for 'in_addr_t' and 'struct in6_addr'.

Also, let's include "ap_session.h" so that we don't need a forward
declaration for 'struct ap_session'.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

accel-pppd/radius/radius.h

 #ifndef __RADIUS_H
 #define __RADIUS_H
 
+#include <netinet/in.h>
 #include <stdint.h>
 #include <sys/time.h>
 
+#include "ap_session.h"
+#include "list.h"
+
 #define REQ_LENGTH_MAX 4096
 
 #define ATTR_TYPE_INTEGER 0
@@ -112,8 +116,6 @@ struct rad_plugin_t
 	int (*send_accounting_request)(struct rad_plugin_t *, struct rad_packet_t *pack);
 };
 
-struct ap_session;
-
 void rad_register_plugin(struct ap_session *, struct rad_plugin_t *);
 
 struct rad_dict_attr_t *rad_dict_find_attr(const char *name);