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/asm-generic/unistd.h b/libc/kernel/uapi/asm-generic/unistd.h
index 52f0b57..fddf1d0 100644
--- a/libc/kernel/uapi/asm-generic/unistd.h
+++ b/libc/kernel/uapi/asm-generic/unistd.h
@@ -113,8 +113,10 @@
 #define __NR_splice 76
 #define __NR_tee 77
 #define __NR_readlinkat 78
+#if defined(__ARCH_WANT_NEW_STAT) || defined(__ARCH_WANT_STAT64)
 #define __NR3264_fstatat 79
 #define __NR3264_fstat 80
+#endif
 #define __NR_sync 81
 #define __NR_fsync 82
 #define __NR_fdatasync 83
@@ -329,8 +331,10 @@
 #define __NR_ftruncate __NR3264_ftruncate
 #define __NR_lseek __NR3264_lseek
 #define __NR_sendfile __NR3264_sendfile
+#if defined(__ARCH_WANT_NEW_STAT) || defined(__ARCH_WANT_STAT64)
 #define __NR_newfstatat __NR3264_fstatat
 #define __NR_fstat __NR3264_fstat
+#endif
 #define __NR_mmap __NR3264_mmap
 #define __NR_fadvise64 __NR3264_fadvise64
 #ifdef __NR3264_stat
@@ -345,8 +349,10 @@
 #define __NR_ftruncate64 __NR3264_ftruncate
 #define __NR_llseek __NR3264_lseek
 #define __NR_sendfile64 __NR3264_sendfile
+#if defined(__ARCH_WANT_NEW_STAT) || defined(__ARCH_WANT_STAT64)
 #define __NR_fstatat64 __NR3264_fstatat
 #define __NR_fstat64 __NR3264_fstat
+#endif
 #define __NR_mmap2 __NR3264_mmap
 #define __NR_fadvise64_64 __NR3264_fadvise64
 #ifdef __NR3264_stat