Update to v5.0 kernel headers.

Test: Builds and boots on taimen.
Change-Id: I13843bf1ab30ea89a50852adc88f2cba8401bded
diff --git a/libc/kernel/uapi/linux/net_namespace.h b/libc/kernel/uapi/linux/net_namespace.h
index b1d96f6..a54c9e1 100644
--- a/libc/kernel/uapi/linux/net_namespace.h
+++ b/libc/kernel/uapi/linux/net_namespace.h
@@ -24,6 +24,8 @@
   NETNSA_NSID,
   NETNSA_PID,
   NETNSA_FD,
+  NETNSA_TARGET_NSID,
+  NETNSA_CURRENT_NSID,
   __NETNSA_MAX,
 };
 #define NETNSA_MAX (__NETNSA_MAX - 1)