An incorrect 'table_map' containing both the table itself,
and possible any outer-refs if this was the last table in
the subquery, was presented to make_cond_for_table().
As a pushed condition is only able to refer column from the table
the condition is pushed to, nothing else than columns from the
table itself (tab->table->map) may be refered in the pushed condition
constructed by 'push_cond= make_cond_for_table()'.
Also fix a minor 'copy and paste' bug in a comment
inside make_cond_for_table().
No testcase is possible on mainbranch as the NDB engine is not available (yet)
on mysql >= 5.5
