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/if_addr.h b/libc/kernel/uapi/linux/if_addr.h
index 0a4b0ae..6a6b640 100644
--- a/libc/kernel/uapi/linux/if_addr.h
+++ b/libc/kernel/uapi/linux/if_addr.h
@@ -38,6 +38,7 @@
   IFA_MULTICAST,
   IFA_FLAGS,
   IFA_RT_PRIORITY,
+  IFA_TARGET_NETNSID,
   __IFA_MAX,
 };
 #define IFA_MAX (__IFA_MAX - 1)