Turn on build/header_guard in cpplint.

Set the correct root path in CPPLINT.cfg and fix existing violations.

Test: tools/repohooks/tools/cpplint.py --quiet system/update_engine/**/*.h
Change-Id: I37812854a68116c69bcef28f8b15856b89a07c4d
diff --git a/parcelable_update_engine_status.h b/parcelable_update_engine_status.h
index 82006e4..3feac76 100644
--- a/parcelable_update_engine_status.h
+++ b/parcelable_update_engine_status.h
@@ -14,8 +14,8 @@
 // limitations under the License.
 //
 
-#ifndef UPDATE_ENGINE_UPDATE_ENGINE_STATUS_H_
-#define UPDATE_ENGINE_UPDATE_ENGINE_STATUS_H_
+#ifndef UPDATE_ENGINE_PARCELABLE_UPDATE_ENGINE_STATUS_H_
+#define UPDATE_ENGINE_PARCELABLE_UPDATE_ENGINE_STATUS_H_
 
 #include <binder/Parcelable.h>
 #include <utils/String16.h>
@@ -60,4 +60,4 @@
 }  // namespace brillo
 }  // namespace android
 
-#endif  // UPDATE_ENGINE_UPDATE_ENGINE_STATUS_H_
+#endif  // UPDATE_ENGINE_PARCELABLE_UPDATE_ENGINE_STATUS_H_