Comment 6 for bug 585628

Analysis:

Fix for Bug 585644,585628

There was problem in dependency flags setting in a table which is
used to sort tables automatically in case of straght_join option.
These dependency flags are set in simplify_join method.
For a case like (a join b) LEFT JOIN c, c was not getting set to
depend on both a AND b, it was getting set only for either a or b,
as specified in original query.
Fixed it properly. Both bug queries now works fine and
also tested some subquery tests, all looks clean.