fix: Establish LDAP connections implicitly

Unfortunately, Centos 7 provides only openssl 1.0.2 (at lest if we
disregard epel), so we can't build the bundled libldap & libsasl2.
"Okay", one might think, "we can link against the distro's libs".
Well, turns out libldap 2.4, which is what we have to deal with in
that case, doesn't have ldap_connect!

Luckily, we don't have to connect explicitly. According to man pages:

```
ldap_init() acts just like ldap_open(), but does not open a connection
to the LDAP server.  The actual connection open will occur when the
first operation is attempted.

ldap_initialize()  acts  like ldap_init()...
```

This is still true for libldap up to and including version 2.6.

NO_DOC=picodata internal patch
NO_CHANGELOG=picodata internal patch
NO_TEST=picodata internal patch