Issue #845542 by pounard: db_query_temporary() will fail without CREATE TEMPORARY TABLES permission on MySQL, update install documentation for that

INSTALL.mysql.txt

@@ -20,8 +20,8 @@ initial database files. Next you must login and set the access database rights:
 Again, you will be asked for the 'username' database password. At the MySQL
 prompt, enter following command:
 
-  GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, INDEX, ALTER
-  ON databasename.*
+  GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, INDEX, ALTER,
+  CREATE TEMPORARY TABLES ON databasename.*
   TO 'username'@'localhost' IDENTIFIED BY 'password';
 
 where