Default is "var/tmp" 


mysql-test/r/myisam.result:
  Update result file
mysql-test/t/myisam.test:
  If running test suite with a non standard tmp dir, the "show create table" will print "DATA DIRECTORY="
  Use replace_result to mask it out
  Set tmpdir to var/log to get the printout of DATA DIRECTORY also when running with standard tmpdir