Improve ssl_log_cxerror():

Fix logic of APLOG_IS_LEVEL check.
Use X509_NAME_print_ex() instead of deprecated X509_NAME_oneline().
Use i2a_ASN1_INTEGER for printing the serial number.
Add notBefore and notAfter dates to log line.
Check for null cert argument (addresses PR 47408).


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1157712 13f79535-47bb-0310-9956-ffa450edef68