mysql-test/mysql-test-run.pl:
  Append mysqltest-time to mysqltest.log at the end of each test case, thus making it possibel to run the whole testsuite with --valgrind-mysqltest and then check the valgrind ouput in mysqltest.log
  Don't valgrind mysqld when only --valgrind-mysqltest is specified
  Fix usage --valgrind, will only valgrind mysqld(that's how it was, I didn't change)