Fix sleep() synchronisation in innodb_information_schema test case.

mysql-test/t/innodb_information_schema.test:
  Using sleep for synchronisation does not work!!!
  Replace by looping until the required condition is met.
sql-common/client.c:
  mysql_ssl_set() did not free old pointers before overwriting with new ones (happens when
  mysql_ssl_set() is called twice without calling mysql_close() in-between).
  
  This sometimes caused memory leaks in the slave depending on exact timing of
  master/slave shutdown.
  
  Fixed by freeing old pointers before installing new ones in mysql_ssl_set(), just like
  mysql_options() does.