Add Database_qualified_name::copy()

  /* We have to copy strings to get them into the right memroot. */

  m_db.length= spname->m_db.length;

  m_db.str= strmake_root(thd->mem_root, spname->m_db.str, spname->m_db.length);

  m_name.length= spname->m_name.length;

  m_name.str= strmake_root(thd->mem_root, spname->m_name.str,

                           spname->m_name.length);

void Database_qualified_name::copy(MEM_ROOT *mem_root,

                                   const LEX_CSTRING &db,

                                   const LEX_CSTRING &name)

{

  m_db.length= db.length;

  m_db.str= strmake_root(mem_root, db.str, db.length);

  m_name.length= name.length;

  m_name.str= strmake_root(mem_root, name.str, name.length);

}