MFC r248776:

MFC r248776:
  Fix interval-based rotations when the -t flag is used. In this case, find
  the most-recently archived logfile and use its mtime to determine whether
  or not to rotate, as in the non-timestamped case.

  Previously we would just try to use the mtime of <logfile>.0, which always
  results in a rotation since it generally doesn't exist in the -t case.

Approved by:	emaste

git-svn-id: svn://svn.freebsd.org/base/stable/8@250479 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f