connlimit: make connlimit.h self-contained

We need to include <stdint.h> to define 'uint*_t' and <string.h> for
'memcpy'.
Signed-off-by: NGuillaume Nault <g.nault@alphalink.fr>

accel-pppd/include/connlimit.h

 #ifndef __CONNLIMIT_H
 #define __CONNLIMIT_H
 
+#include <stdint.h>
+#include <string.h>
+
 static inline uint64_t cl_key_from_ipv4(uint32_t ip)
 {
 	return ip;