Store SSL certificates in LDAP, get rid of reified vhosts

[andersk]

This will need patches to Apache, mod_ssl, and mod_vhost_ldap.

From a quick look at my Git repo from four years ago, my plan was

• turn check_hostalias (server/vhost.c) into an generic ap_lookup_vhost API;
• use ap_lookup_vhost to replace ssl_find_vhost (modules/ssl/ssl_engine_kernel.c);
• add a lookup_vhost hook to ap_lookup_vhost that can be implemented by modules;
• implement the lookup_vhost hook in mod_vhost_ldap (replacing the current translate_name hook);
• teach mod_vhost_ldap an equivalent of the SSLCertificate{File,KeyFile?,ChainFile?} directives.

Hopefully most of this work will be upstreamable. I haven’t checked whether the plan needs changes for httpd 2.4 (if so, it’s not worth putting any effort into 2.2).

[ Partial dup of #52. ]

[geofft]

Can you link to your git repo (if you still have it)? I might be able to pick this up