remove redundant "body" from Event_parse_data (use sp_head::m_body).


sql/event_data_objects.cc:
  Use sp_head::m_body to store SQL-statement.
  Polishing.
sql/event_data_objects.h:
  Use sp_head::m_body to store SQL-statement.
  Polishing.
sql/event_db_repository.cc:
  Use sp_head::m_body to store SQL-statement.
sql/sql_yacc.yy:
  Use sp_head::m_body to store SQL-statement.