sys/socket.h: add SO_DETACH_REUSEPORT_BPF from linux v5.3

see

  linux commit 99f3a064bc2e4bd5fe50218646c5be342f2ad18c
  bpf: net: Add SO_DETACH_REUSEPORT_BPF

include/sys/socket.h

@@ -288,6 +288,7 @@ struct linger {
 #define SO_TXTIME               61
 #define SCM_TXTIME              SO_TXTIME
 #define SO_BINDTOIFINDEX        62
+#define SO_DETACH_REUSEPORT_BPF 68
 
 #ifndef SOL_SOCKET
 #define SOL_SOCKET      1