logrotate.pp should support dateext and related parameters.
By this change, a filename of a rotated file can be easily distinguished
by rotated date.
Change-Id: I798304a472df41b86a88611c97c2c99131faa0ad
(cherry picked from commit 1eafeb67bf)
(cherry picked from commit 964fe8cc62)
(cherry picked from commit 9d62bf52a4)