add getcommitdata to wireproto capabilities

Summary: This allows the client to do proper feature detection.

Reviewed By: krallin

Differential Revision: D20910379

fbshipit-source-id: c7b9d4073e94518835b39809caf8b068f70cbc2f

eden/mononoke/repo_client/src/client/mod.rs

@@ -220,6 +220,7 @@ fn wireprotocaps() -> Vec<String> {
         "treeonly".to_string(),
         "knownnodes".to_string(),
         "designatednodes".to_string(),
+        "getcommitdata".to_string(),
     ]
 }