Write test results to var/log
Add test for "source" and variable expansion


client/mysqltest.c:
  Improve error messages
  Write .reject file to the location specified by --logdir
mysql-test/mysql-test-run.pl:
  Pass logdir to mysqltest, to get test results written to var/log
mysql-test/r/mysqltest.result:
  Update test results
mysql-test/t/mysqltest.test:
  Add test for "source" and variable expansion
  Update test after writing result in var/log