The change for MCOL-4264 erroneously added the "lock_type" member
to cal_connection_info, which is shared between multiple tables.
So some tables that were opened for write erroneously identified
themselves as read only.
Moving the member to ha_mcs instead.
For certain queries, such as:
update cs1 set i = 41 where i = 42 or (i is null and 42 is null);
the SELECT_LEX.where does not contain the required where conditions.
Server sends the where conditions in the call to cond_push(), so
we are storing them in a handler data member, condStack, and later
push them down to getSelectPlan() for UPDATES/DELETEs.
