Added --skip-im option handling
  Don't terminate script if IM fails to create PID file
mtr_cases.pl:
  Added --skip-im option handling
mtr_process.pl:
  Kill left over 'mysqld' processes started by IM


mysql-test/lib/mtr_process.pl:
  Kill left over 'mysqld' processes started by IM
mysql-test/lib/mtr_cases.pl:
  Added --skip-im option handling
mysql-test/mysql-test-run.pl:
  Added --skip-im option handling
  Don't terminate script if IM fails to create PID file