so that extra slashes are handled in tmpdir. (Bug #8497)


sql/ha_heap.cc:
  use constants instead of magic integers on fn_format() calls
sql/sql_select.cc:
  Construct filename for temporary tables using fn_format() to get consistent
  filenames.
mysql-test/t/temp_table.test:
  Add new regression test
mysql-test/r/temp_table.result:
  Add new test results