CRL loading fails due to incorrect return code check

[smarsching]

When specifying a CRL through the crl_path option in the API listener configuration, starting Icinga2 fails with the following error message:

critical/SSL: Error loading crl file '/etc/icinga2/pki/crl.pem': 0, "error:00000000:lib(0):func(0):reason(0)"

The reason for this error message is that AddCRLToSSLContext in lib/base/tlsutility.cpp incorrectly verifies the return code of the OpenSSL function X509_LOOKUP_load_file. OpenSSL signals successful execution with a return code of one, but the code in AddCRLToSSLContext fails if the return code is not zero. This means that the code will not continue when the CRL has actually been loaded successfully, but it will continue when there is an error while loading the CRL.

I found this bug in Icinga 2.4, but it is still present in the current master branch.

Don't bother fixing this bug. I already have a patch and will submit a pull request shortly. This issue is only for tracking the bug.