Save no-records constant tables in JOIN::const_table_map before we invoke
eliminate_tables(). Failure to do so caused crash when the same table was
marked as constant two times

mysql-test/r/table_elim.result:
  LPBUG#524025 Running RQG outer_join test leads to crash
  - Testcase
mysql-test/t/table_elim.test:
  LPBUG#524025 Running RQG outer_join test leads to crash
  - Testcase
sql/sql_select.cc:
  LPBUG#524025 Running RQG outer_join test leads to crash
  Save no-records constant tables in JOIN::const_table_map before we invoke eliminate_tables(). Failure to do so caused crash when the same table was marked as constant two times.