prevent possible segv in ssl_init_CheckServers if s->addrs is NULL.

for example: <VirtualHost *:>, for which the core only spits out a warning:
 Name or service not known: Cannot resolve host name *: --- ignoring!


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk/modules/ssl@95158 13f79535-47bb-0310-9956-ffa450edef68