Add include_defs('//bucklets/gerrit_plugin.bucklet') to buck

Change-Id: I081b9d69a5e29786f82f511eb2bb839552d894b3
diff --git a/BUCK b/BUCK
index 2ea01c2..abef774 100644
--- a/BUCK
+++ b/BUCK
@@ -1,3 +1,5 @@
+include_defs('//bucklets/gerrit_plugin.bucklet')
+
 MODULE = 'com.googlesource.gerrit.plugins.menuextender.MenuExtenderPlugin'
 
 gerrit_plugin(