spanner/spannertest: update signature of Server.UpdateDDL

This was an oversight in the previous change. The natural type for
spansql.DDL is now the pointer type (it is what is returned by
ParseDDL), so functions accepting that type should match.

Change-Id: I5a4f15df9d2963fd227fa9d203a5fd662a1e7d95
Reviewed-on: https://code-review.googlesource.com/c/gocloud/+/51111
Reviewed-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Knut Olav Løite <koloite@gmail.com>
diff --git a/spanner/spannertest/inmem.go b/spanner/spannertest/inmem.go
index 234f75f..10ed4d4 100644
--- a/spanner/spannertest/inmem.go
+++ b/spanner/spannertest/inmem.go
@@ -244,7 +244,7 @@
 // This is a convenience method for tests that may assume an existing schema.
 // The more general approach is to dial this server using an admin client, and
 // use the UpdateDatabaseDdl RPC method.
-func (s *Server) UpdateDDL(ddl spansql.DDL) error {
+func (s *Server) UpdateDDL(ddl *spansql.DDL) error {
 	ctx := context.Background()
 	for _, stmt := range ddl.List {
 		if st := s.s.runOneDDL(ctx, stmt); st.Code() != codes.OK {