led to creating corrupted index.

While execution of the  CREATE .. SELECT SQL_BUFFER_RESULT statement the 
engine->start_bulk_insert function was called twice. On the first call
On the first call MyISAM disabled all non-unique indexes and on the second
call it decides to not re-enable them because all indexes was disabled.
Due to this no indexes was actually created during CREATE TABLE thus
producing crashed table.

Now the select_inset class has is_bulk_insert_mode flag which prevents
calling the start_bulk_insert function twice.
The flag is set in the select_create::prepare, select_insert::prepare2
functions and the select_insert class constructor.
The flag is reset in the select_insert::send_eof function.


mysql-test/t/insert_select.test:
  A test case is added for the bug#30384: Having SQL_BUFFER_RESULT option in the
  CREATE .. KEY(..) .. SELECT led to creating corrupted index.
mysql-test/r/insert_select.result:
  A test case is added for the bug#30384: Having SQL_BUFFER_RESULT option in the 
  CREATE .. KEY(..) .. SELECT led to creating corrupted index.
sql/sql_class.h:
  Bug#30384: Having SQL_BUFFER_RESULT option in the CREATE .. KEY(..) .. SELECT
  led to creating corrupted index.
  The is_bulk_insert_mode flag is added to the select_insert class.
sql/sql_insert.cc:
  Bug#30384: Having SQL_BUFFER_RESULT option in the CREATE .. KEY(..) .. SELECT
  led to creating corrupted index.
  The is_bulk_insert_mode is set in the select_create::prepare, select_insert::prepare2
  functions and the select_insert class constructor.
  The flag is reset in the select_insert::send_eof function.