Improve code that detects if ndb shuold be installed
Remove call to stop_all_servers after install db, if any servers are still running 
and need to be stopped they will be stopped atuomatically


mysql-test/lib/mtr_cases.pl:
  All tests that have "source include/have_ndb.inc" are ndb tests
mysql-test/mysql-test-run.pl:
  Set --with-ndbcluster to only be valid together with --bench
  Rename opt_ndbcluster_supported to glob_ndbcluster_supported it's not an option
  Fix warnings