Update to v4.17.3 kernel headers.

Test: Builds, boots on a walleye.
Change-Id: I389d8b61ec00ea309e38d1b1a2e0dace48c21edb
diff --git a/libc/kernel/uapi/linux/msg.h b/libc/kernel/uapi/linux/msg.h
index 89d8d38..20d8d4f 100644
--- a/libc/kernel/uapi/linux/msg.h
+++ b/libc/kernel/uapi/linux/msg.h
@@ -21,6 +21,7 @@
 #include <linux/ipc.h>
 #define MSG_STAT 11
 #define MSG_INFO 12
+#define MSG_STAT_ANY 13
 #define MSG_NOERROR 010000
 #define MSG_EXCEPT 020000
 #define MSG_COPY 040000