update_engine: fixed warnings from cpplint

Fixed all the cpplint warnings in update engine.

BUG=None
TEST=Unit tests still pass.

Change-Id: I285ae858eec8abe0b26ff203b99a42a200ceb71c
Reviewed-on: https://chromium-review.googlesource.com/204027
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/postinstall_runner_action.cc b/postinstall_runner_action.cc
index cc8968b..86b7501 100644
--- a/postinstall_runner_action.cc
+++ b/postinstall_runner_action.cc
@@ -38,7 +38,7 @@
                                            &temp_rootfs_dir_));
   ScopedDirRemover temp_dir_remover(temp_rootfs_dir_);
 
-  unsigned long mountflags = MS_RDONLY;
+  unsigned long mountflags = MS_RDONLY;  // NOLINT(runtime/int)
   int rc = mount(install_device.c_str(),
                  temp_rootfs_dir_.c_str(),
                  "ext2",