MDEV-8954 unnecessary fetch of entire table

Merged fix into 10.2.

storage/spider/spd_db_mysql.h

@@ -1128,6 +1128,9 @@ public:
     ulong sql_type,
     int link_idx
   );
+  bool is_sole_projection_field(
+      uint16 field_index
+  );
   bool is_bulk_insert_exec_period(
     bool bulk_end
   );