Don't exit daemon if opening or parsing the CRL fails.

Don't exit daemon if opening or parsing the CRL fails.

As requested in trac ticket #83, the daemon should not exit if opening the
CRL file during a connection attempt fails; OpenVPN should merely deny the
connection.

CRL files need to be periodically updated. When users update their CRL in
place and a connection attempt takes place simultaneously, the CRL file
might temporarily not be available, or not be in a consistent state.
Previously, that would result in the daemon exiting. With this patch, that
results in one (or possibly a few) failed connection attempts, but service
will restore automatically as soon as the CRL is again available in a valid
state.

Note that on startup OpenVPN still checks the existence and accessibility
of the CRL file, and will refuse to start on error.

While I was touching the code, I improved error reporting for the PolarSSL
code a bit. The polar code opens and parses the CRL in a single call, so
on error retrieve details from polarssl and report those to the user.

Signed-off-by: Steffan Karger <steffan.karger@fox-it.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <53BED57C.7070300@fox-it.com>
Signed-off-by: Gert Doering <gert@greenie.muc.de>