Update to v4.19 kernel headers.

Test: Builds and boots.
Change-Id: I99a9ed79666e143b47f02ca4e59eed94f69b7e4a
(cherry picked from commit a981e2e52e2e95a65fa9c9b6fb16dcb4c83dd576)
diff --git a/libc/kernel/uapi/linux/aio_abi.h b/libc/kernel/uapi/linux/aio_abi.h
index e71936d..17ca2f9 100644
--- a/libc/kernel/uapi/linux/aio_abi.h
+++ b/libc/kernel/uapi/linux/aio_abi.h
@@ -27,11 +27,13 @@
   IOCB_CMD_PWRITE = 1,
   IOCB_CMD_FSYNC = 2,
   IOCB_CMD_FDSYNC = 3,
+  IOCB_CMD_POLL = 5,
   IOCB_CMD_NOOP = 6,
   IOCB_CMD_PREADV = 7,
   IOCB_CMD_PWRITEV = 8,
 };
 #define IOCB_FLAG_RESFD (1 << 0)
+#define IOCB_FLAG_IOPRIO (1 << 1)
 struct io_event {
   __u64 data;
   __u64 obj;