JENKINS-15178: Enabled log rotation on Mac OSX

Enabled log rotation on Mac OS X, that fixes problem pointed out at [#15178 Comment](https://issues.jenkins-ci.org/browse/JENKINS-15178?focusedCommentId=172644&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-172644)