Update to v4.19 kernel headers.

Test: Builds and boots.
Change-Id: I99a9ed79666e143b47f02ca4e59eed94f69b7e4a
(cherry picked from commit a981e2e52e2e95a65fa9c9b6fb16dcb4c83dd576)
diff --git a/libc/kernel/uapi/asm-mips/asm/sembuf.h b/libc/kernel/uapi/asm-mips/asm/sembuf.h
index 25979ac..a46f326 100644
--- a/libc/kernel/uapi/asm-mips/asm/sembuf.h
+++ b/libc/kernel/uapi/asm-mips/asm/sembuf.h
@@ -18,6 +18,7 @@
  ****************************************************************************/
 #ifndef _ASM_SEMBUF_H
 #define _ASM_SEMBUF_H
+#ifdef __mips64
 struct semid64_ds {
   struct ipc64_perm sem_perm;
   __kernel_time_t sem_otime;
@@ -26,4 +27,14 @@
   unsigned long __unused1;
   unsigned long __unused2;
 };
+#else
+struct semid64_ds {
+  struct ipc64_perm sem_perm;
+  unsigned long sem_otime;
+  unsigned long sem_ctime;
+  unsigned long sem_nsems;
+  unsigned long sem_otime_high;
+  unsigned long sem_ctime_high;
+};
+#endif
 #endif