Update to v4.17.3 kernel headers.

Test: Builds, boots on a walleye.
Change-Id: I389d8b61ec00ea309e38d1b1a2e0dace48c21edb
diff --git a/libc/kernel/uapi/linux/time.h b/libc/kernel/uapi/linux/time.h
index 59e3160..b75d2dc 100644
--- a/libc/kernel/uapi/linux/time.h
+++ b/libc/kernel/uapi/linux/time.h
@@ -45,6 +45,10 @@
   struct timeval it_interval;
   struct timeval it_value;
 };
+struct __kernel_old_timeval {
+  __kernel_long_t tv_sec;
+  __kernel_long_t tv_usec;
+};
 #define CLOCK_REALTIME 0
 #define CLOCK_MONOTONIC 1
 #define CLOCK_PROCESS_CPUTIME_ID 2