Add missing includes for getpeername.

getpeername(2) requires <sys/socket.h> which on some systems also
requires <sys/types.h>. Include both to avoid compilation warnings.

src/cluster.c

@@ -31,6 +31,8 @@
 #include "redis.h"
 #include "endianconv.h"
 
+#include <sys/types.h>
+#include <sys/socket.h>
 #include <arpa/inet.h>
 #include <fcntl.h>
 #include <unistd.h>