Fix Eclipse project generation

When generating the Eclipse project, the reference to the
gerrit-plugin-api was not added.

Change-Id: I583f2eb386b4cf92857c7570ebc66ca423af3001
diff --git a/BUCK b/BUCK
index 329a066..aa49004 100644
--- a/BUCK
+++ b/BUCK
@@ -18,5 +18,7 @@
 
 java_library(
   name = 'classpath',
-  deps = [':delete-project__plugin'],
+  deps = GERRIT_PLUGIN_API + [
+    ':delete-project__plugin',
+  ],
 )