CRL: use time_t instead of struct timespec to store last mtime

CRL: use time_t instead of struct timespec to store last mtime

As of now, we store the last mtime for the CRL file in a timespec
object. However we store seconds only and we ignore the subsecond
field (this came into being because not all platforms have nanoseconds
precision in timespec).

Given the above, we can safely replace the timespec object with a
simple time_t.

Reported-by: Gert Doering <gert@greenie.muc.de>
Signed-off-by: Antonio Quartulli <a@unstable.cc>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20170316082117.21020-1-a@unstable.cc>
URL: http://www.mail-archive.com/search?l=mid&q=20170316082117.21020-1-a@unstable.cc
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit f3705dd1e711ee9f8546b841e4b18e9e9a224975)