Update to v5.0 kernel headers.

Test: Builds and boots on taimen.
Change-Id: I13843bf1ab30ea89a50852adc88f2cba8401bded
diff --git a/libc/kernel/uapi/linux/if_tun.h b/libc/kernel/uapi/linux/if_tun.h
index 6a3c75e..cb2d2d2 100644
--- a/libc/kernel/uapi/linux/if_tun.h
+++ b/libc/kernel/uapi/linux/if_tun.h
@@ -51,6 +51,7 @@
 #define TUNGETVNETBE _IOR('T', 223, int)
 #define TUNSETSTEERINGEBPF _IOR('T', 224, int)
 #define TUNSETFILTEREBPF _IOR('T', 225, int)
+#define TUNSETCARRIER _IOW('T', 226, int)
 #define IFF_TUN 0x0001
 #define IFF_TAP 0x0002
 #define IFF_NAPI 0x0010