New tests for prepared statements:

- 'ps_10nestset' uses a "nested set" approach for an employee 
  hierarchy, then does arithmetic on the "salary" field;
  (soon) to be extended by inserts / deletes which imply
  mass updates on the "l"/"r" fields showing the set inclusion,
- 'ps_11bugs' will get (some of ?) those bug DB entries which
  refer to prepared statements, but whose number does not appear
  in a test file comment - so it will also be extended.

mysql-test/r/ps_11bugs.result

@@ -0,0 +1,21 @@
+use test;
+drop table if exists test_select;
+Warnings:
+Note	1051	Unknown table 'test_select'
+CREATE TABLE test_select(session_id  char(9) NOT NULL);
+INSERT INTO test_select VALUES ("abc");
+SELECT * FROM test_select;
+session_id
+abc
+prepare st_1180 from 'SELECT * FROM test_select WHERE ?="1111" and session_id = "abc"';
+set @arg1= 'abc';
+execute st_1180 using @arg1;
+session_id
+set @arg1= '1111';
+execute st_1180 using @arg1;
+session_id
+abc
+set @arg1= 'abc';
+execute st_1180 using @arg1;
+session_id
+drop table test_select;