mysql-test/lib/mtr_process.pl:
  Remove junk code/comments
  Moved the creation of var/log out of function mtr_kill_leftovers
mysql-test/mysql-test-run.pl:
  Rename 'kill_running_server' to more appropriate name 'kill_running_servers'
  If no var/log dir exists when mtr_kill_leftovers is started it should be created
  Remove "unless" syntax, too perlish
  Fix typo