update_engine: Sort headers alphabetically (build/include_alpha)

We are going to enable build/include_alpha linter warning soon,
so in preparation for this, fixed the warnings in update_engine.

BUG=None
TEST=cpplint.py --filter=-build/include_order,+build/include_alpha update_engine/*
CQ-DEPEND=CL:209472

Change-Id: I261ea04681599a68ec7cb899f2f881cbe228ff7b
Reviewed-on: https://chromium-review.googlesource.com/209631
Reviewed-by: Alex Deymo <deymo@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/omaha_request_action.h b/omaha_request_action.h
index 8b6c41b..c289793 100644
--- a/omaha_request_action.h
+++ b/omaha_request_action.h
@@ -5,9 +5,9 @@
 #ifndef UPDATE_ENGINE_OMAHA_REQUEST_ACTION_H_
 #define UPDATE_ENGINE_OMAHA_REQUEST_ACTION_H_
 
+#include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
-#include <fcntl.h>
 
 #include <string>
 #include <vector>