Add a missing index for the ChangeAccess.submitted query

Signed-off-by: Shawn O. Pearce <sop@google.com>
diff --git a/appdist/src/main/sql/query_index.sql b/appdist/src/main/sql/query_index.sql
index 9aa122d..aa741c8 100644
--- a/appdist/src/main/sql/query_index.sql
+++ b/appdist/src/main/sql/query_index.sql
@@ -78,6 +78,10 @@
 CREATE INDEX changes_byOwnerStatus
 ON changes (owner_account_id, open, last_updated_on DESC);
 
+--    covers:             submitted
+CREATE INDEX changes_submitted
+ON changes (dest_project_name, dest_branch_name, status, last_updated_on);
+
 
 -- *********************************************************************
 -- ChangeApprovalAccess