Lift limitation for merging VIEWS with Subqueries in SELECT_LIST and test it

Also see http://ru-mysql.livejournal.com/287623.html?nojs=1

Patch is like this (+ variable to control)

bell@desktop:~/maria/bzr/work-maria-5.5-test/mysql-test$ bzr diff
=== modified file 'sql/sql_lex.cc'
— sql/sql_lex.cc 2012-08-27 16:13:17 +0000
+++ sql/sql_lex.cc 2012-11-16 09:48:33 +0000
@@ -2578,6 +2578,7 @@ bool LEX::can_be_merged()
if (tmp_unit->first_select()->parent_lex == this &&
(tmp_unit->item == 0 ||
(tmp_unit->item->place() != IN_WHERE &&
+ tmp_unit->item->place() != SELECT_LIST &&
tmp_unit->item->place() != IN_ON)))
{
selects_allow_merge= 0;

then use random Query Generator to test it.