Add missing @Override to DroidDoc and ApiCheck

Change-Id: Ic7829a4ea62a614ef8b525bd84f8fbaaa4674d06
diff --git a/tools/droiddoc/src/SourcePositionInfo.java b/tools/droiddoc/src/SourcePositionInfo.java
index 6244803..ac605ec 100644
--- a/tools/droiddoc/src/SourcePositionInfo.java
+++ b/tools/droiddoc/src/SourcePositionInfo.java
@@ -76,6 +76,7 @@
         return new SourcePositionInfo(that.file, line, 0);
     }
 
+    @Override
     public String toString()
     {
         return file + ':' + line;