two timestamp fields.
  
The actual problem here was that CREATE TABLE allowed zero
date as a default value for a TIMESTAMP column in NO_ZERO_DATE mode.
  
The thing is that for TIMESTAMP date type specific rule is applied:
  column_name TIMESTAMP == column_name TIMESTAMP DEFAULT 0
whever for any other date data type
  column_name TYPE == column_name TYPE DEFAULT NULL
  
The fix is to raise an error when we're in NO_ZERO_DATE mode and
there is TIMESTAMP column w/o default value.


mysql-test/r/create.result:
  Update result file.
mysql-test/t/create.test:
  Test case for Bug#18834: ALTER TABLE ADD INDEX on table with
  two timestamp fields.
sql/sql_table.cc:
  Report an error if NO_ZERO_MODE is set and we have zero date
  as a default.