[ale] Periodically check that we're writing to the same file.

This can be used to have external tools like logrotate handle log
rotation.

Change-Id: Ida82eac625b86b7fb09a28391234ea4290f46f12
Reviewed-on: http://review.couchbase.org/37749
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>