Update to v4.17.3 kernel headers.

Test: Builds, boots on a walleye.
Change-Id: I389d8b61ec00ea309e38d1b1a2e0dace48c21edb
diff --git a/libc/kernel/uapi/linux/tcp.h b/libc/kernel/uapi/linux/tcp.h
index 0bf9559..8b73119 100644
--- a/libc/kernel/uapi/linux/tcp.h
+++ b/libc/kernel/uapi/linux/tcp.h
@@ -186,6 +186,9 @@
   TCP_NLA_MIN_RTT,
   TCP_NLA_RECUR_RETRANS,
   TCP_NLA_DELIVERY_RATE_APP_LMT,
+  TCP_NLA_SNDQ_SIZE,
+  TCP_NLA_CA_STATE,
+  TCP_NLA_SND_SSTHRESH,
 };
 #define TCP_MD5SIG_MAXKEYLEN 80
 #define TCP_MD5SIG_FLAG_PREFIX 1