- Avoid defaault log file names looking like <hostname>.pid.slow.log
  by using the FN_REPLACE_EXT flag to 'fn_format'
 - Remove the default log files generated by log_state.test before
   test completes


mysql-test/t/log_state.test:
  Tess sets location of log files to default location ie. they will be
  created in var/run form which the mysqld was started. Remove the
  files when test are completed
sql/log.cc:
  Replace the extension formatting the default log file name
  from "pidfile_name" which already contains an extension