Update to v4.20.1 kernel headers.

This includes one manual change:

In the file bionic/libc/kernel/uapi/linux/in.h, the macro IN_BADCLASS
was not definied correctly. Change the macro from:

  #define IN_BADCLASS(a) ((((long int) (a)) == 0xffffffff)

to:

  #define IN_BADCLASS(a) (((long int) (a)) == (long int)0xffffffff)

This change is being pushed to the upstream kernels.

Test: Builds and boots.
Change-Id: Ia304773a9dc6789b34d9769d73742384d6afb571
Merged-In: Ia304773a9dc6789b34d9769d73742384d6afb571
(cherry picked from commit 967fb01cce73591281e7804e2c0fa9f83b618f5b)
diff --git a/libc/kernel/uapi/linux/neighbour.h b/libc/kernel/uapi/linux/neighbour.h
index cf32a12..6329211 100644
--- a/libc/kernel/uapi/linux/neighbour.h
+++ b/libc/kernel/uapi/linux/neighbour.h
@@ -51,6 +51,7 @@
 #define NTF_PROXY 0x08
 #define NTF_EXT_LEARNED 0x10
 #define NTF_OFFLOADED 0x20
+#define NTF_STICKY 0x40
 #define NTF_ROUTER 0x80
 #define NUD_INCOMPLETE 0x01
 #define NUD_REACHABLE 0x02