ORDER BY is used

The range analysis module did not correctly signal to the 
handler that a range represents a ref (EQ_RANGE flag). This causes 
non-range queries like 
SELECT ... FROM ... WHERE keypart_1=const, ..., keypart_n=const 
ORDER BY ... FOR UPDATE
to wait for a lock unneccesarily if another running transaction uses
SELECT ... FOR UPDATE on the same table.

Fixed by setting EQ_RANGE for all range accesses that represent 
an equality predicate.