Add OpenBSD default CA certificates file location

GitHub pull: https://github.com/OfflineIMAP/offlineimap/pull/120
Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>
Add default CA bundle location for DragonFlyBSD

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>