include/m_string.h:
  added include to va_list bicame known
mysql-test/r/union.result:
  some changing in error message
sql/sql_base.cc:
  error detection moved
sql/sql_lex.cc:
  new flag to detect table name error
sql/sql_lex.h:
  new flag to detect table name error
sql/sql_yacc.yy:
  check possibility of using table name added