basic/linux: update linux uapi headers

IPPROTO_L2TP was moved from linux/l2tp.h to linux/in.h [0], so let's
reflect that change to fix build with newer kernels:

```
In file included from ../src/libsystemd/sd-netlink/netlink-types-genl.c:10:
../src/basic/linux/l2tp.h:16: error: "IPPROTO_L2TP" redefined [-Werror]
   16 | #define IPPROTO_L2TP            115
      |
In file included from ../src/libsystemd/sd-netlink/netlink-types-genl.c:3:
/usr/include/netinet/in.h:85: note: this is the location of the previous definition
   85 | #define IPPROTO_L2TP            IPPROTO_L2TP
      |
cc1: all warnings being treated as errors
```

When at it, update the rest of the headers we ship as well.

[0] https://github.com/torvalds/linux/commit/65b32f801bfbc54dc98144a6ec26082b59d131ee

src/basic/linux/if_tun.h

@@ -67,6 +67,8 @@
 #define IFF_TAP		0x0002
 #define IFF_NAPI	0x0010
 #define IFF_NAPI_FRAGS	0x0020
+/* Used in TUNSETIFF to bring up tun/tap without carrier */
+#define IFF_NO_CARRIER	0x0040
 #define IFF_NO_PI	0x1000
 /* This flag has no real effect */
 #define IFF_ONE_QUEUE	0x2000
@@ -88,6 +90,8 @@
 #define TUN_F_TSO6	0x04	/* I can handle TSO for IPv6 packets */
 #define TUN_F_TSO_ECN	0x08	/* I can handle TSO with ECN bits. */
 #define TUN_F_UFO	0x10	/* I can handle UFO packets */
+#define TUN_F_USO4	0x20	/* I can handle USO for IPv4 packets */
+#define TUN_F_USO6	0x40	/* I can handle USO for IPv6 packets */
 
 /* Protocol info prepended to the packets (when IFF_NO_PI is not set) */
 #define TUN_PKT_STRIP	0x0001
@@ -108,7 +112,7 @@ struct tun_pi {
 struct tun_filter {
 	__u16  flags; /* TUN_FLT_ flags see above */
 	__u16  count; /* Number of addresses */
-	__u8   addr[0][ETH_ALEN];
+	__u8   addr[][ETH_ALEN];
 };
 
 #endif /* _UAPI__IF_TUN_H */