InnoDB: Adjust error message when a dropped tablespace is accessed.

storage/innodb_plugin/fil/fil0fil.c

@@ -1853,7 +1853,7 @@ fil_inc_pending_ops(
 
 	if (space == NULL) {
 		fprintf(stderr,
-			"InnoDB: Error: trying to do ibuf merge to a"
+			"InnoDB: Error: trying to do an operation on a"
 			" dropped tablespace %lu\n",
 			(ulong) id);
 	}