sys/socket.h: add new SO_ socket options from linux v5.11

see

  linux commit 7fd3253a7de6a317a0683f83739479fb880bffc8
  net: Introduce preferred busy-polling

  linux commit 7c951cafc0cb2e575f1d58677b95ac387ac0a5bd
  net: Add SO_BUSY_POLL_BUDGET socket option

include/sys/socket.h

@@ -289,6 +289,8 @@ struct linger {
 #define SCM_TXTIME              SO_TXTIME
 #define SO_BINDTOIFINDEX        62
 #define SO_DETACH_REUSEPORT_BPF 68
+#define SO_PREFER_BUSY_POLL     69
+#define SO_BUSY_POLL_BUDGET     70
 
 #ifndef SOL_SOCKET
 #define SOL_SOCKET      1