Update to v4.17.3 kernel headers.

Test: Builds, boots on a walleye.
Change-Id: I389d8b61ec00ea309e38d1b1a2e0dace48c21edb
diff --git a/libc/kernel/uapi/linux/tls.h b/libc/kernel/uapi/linux/tls.h
index 925cf80..b6910af 100644
--- a/libc/kernel/uapi/linux/tls.h
+++ b/libc/kernel/uapi/linux/tls.h
@@ -20,6 +20,7 @@
 #define _UAPI_LINUX_TLS_H
 #include <linux/types.h>
 #define TLS_TX 1
+#define TLS_RX 2
 #define TLS_VERSION_MINOR(ver) ((ver) & 0xFF)
 #define TLS_VERSION_MAJOR(ver) (((ver) >> 8) & 0xFF)
 #define TLS_VERSION_NUMBER(id) ((((id ##_VERSION_MAJOR) & 0xFF) << 8) | ((id ##_VERSION_MINOR) & 0xFF))
@@ -33,6 +34,7 @@
 #define TLS_CIPHER_AES_GCM_128_TAG_SIZE 16
 #define TLS_CIPHER_AES_GCM_128_REC_SEQ_SIZE 8
 #define TLS_SET_RECORD_TYPE 1
+#define TLS_GET_RECORD_TYPE 2
 struct tls_crypto_info {
   __u16 version;
   __u16 cipher_type;