Remove fpm_logfile from logrotate script

The default location of fpm_logfile on all operating systems is inside
fpm_log_dir. This causes logrotate to emit a warning every time:

  /etc/cron.daily/logrotate:
  error: php5-fpm:1 duplicate log entry for
    /var/log/php5-fpm/fpm-master.log
  error: found error in /var/log/php5-fpm/fpm-master.log
    /var/log/php5-fpm/*.log , skipping
Merge pull request #2 from StephenKing/fix-logrotate

Remove fpm_logfile from logrotate script