Update to v5.8 kernel headers.

Kernel headers coming from:

Git: https://android.googlesource.com/kernel/common/
Branch: android-mainline
Tag: android-mainline-5.8

Test: NA
Change-Id: I2231c877589820fc09800a200cf4ac62ba74b04c
diff --git a/libc/kernel/uapi/linux/nexthop.h b/libc/kernel/uapi/linux/nexthop.h
index a2a959f..f99a074 100644
--- a/libc/kernel/uapi/linux/nexthop.h
+++ b/libc/kernel/uapi/linux/nexthop.h
@@ -49,6 +49,7 @@
   NHA_ENCAP,
   NHA_GROUPS,
   NHA_MASTER,
+  NHA_FDB,
   __NHA_MAX,
 };
 #define NHA_MAX (__NHA_MAX - 1)