{,vpx_scale}: normalize include guards

Change-Id: Ib8aafeee30d59521ee256dc1801e0db6b4b8a371
diff --git a/ivfdec.h b/ivfdec.h
index b1468a9..5da9acc 100644
--- a/ivfdec.h
+++ b/ivfdec.h
@@ -27,4 +27,4 @@
 }  /* extern "C" */
 #endif
 
-#endif  /* IVFDEC_H_ */
+#endif  // IVFDEC_H_