logrotate: Update to 3.15

logrotate: Update to 3.15

For details see:
https://github.com/logrotate/logrotate/releases

- timer unit: change trigger fuzz from 12h to 1h (#230)
- service unit: only run if /var/log is mounted (#230)
- preserve fractional part of timestamps when compressing (#226)
- re-indent source code using spaces only (#188)
- minage: avoid rounding issue while comparing the amount of seconds (#36)
- never remove old log files if rotate -1 is specified (#202)
- return non-zero exit status if a config file contains an error (#199)
- make copytruncate work with rotate 0 (#191)
- warn user if both size and the time interval options are used (#192)
- pass rotated log file name as the 2nd argument of the postrotate script
  when sharedscript is not enabled (#193)
- rename logrotate-default to logrotate.conf (#187)

Best,
Matthias

Signed-off-by: Matthias Fischer <matthias.fischer@ipfire.org>
Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>