Add missing @Override to DroidDoc and ApiCheck

Change-Id: Ic7829a4ea62a614ef8b525bd84f8fbaaa4674d06
diff --git a/tools/droiddoc/src/AnnotationInstanceInfo.java b/tools/droiddoc/src/AnnotationInstanceInfo.java
index 07d4aa3..c4abc7e 100644
--- a/tools/droiddoc/src/AnnotationInstanceInfo.java
+++ b/tools/droiddoc/src/AnnotationInstanceInfo.java
@@ -35,6 +35,7 @@
         return mElementValues;
     }
 
+    @Override
     public String toString()
     {
         StringBuilder str = new StringBuilder();