Problem: thd->thread_specific_used flag is not set executing a statement
containig connection_id() function using PS protocol, that leads to 
improper binlog event creation.

Fix: set the flag in the Item_func_connection_id::fix_fields().


sql/item_create.cc:
  Fix for bug #30200: mysqlbinlog.test: connection_id() not restored under ps-protocol
    - set the thd->thread_specific_used flag in the Item_func_connection_id::fix_fields()
      to have it properly set using PS protocol as well.
sql/item_func.cc:
  Fix for bug #30200: mysqlbinlog.test: connection_id() not restored under ps-protocol
    - set the thd->thread_specific_used flag in the Item_func_connection_id::fix_fields()
      to have it properly set using PS protocol as well.
sql/sql_parse.cc:
  Fix for bug #30200: mysqlbinlog.test: connection_id() not restored under ps-protocol
    - reset the thd->thread_specific_used flag in the mysql_reset_thd_for_next_command().