Exploit::Remote::LDAP - use socket monkeypatch

The Exploit::Remote::LDAP namespace appears to use the upstream
Net::LDAP implementation which relies on Ruby's native sockets...

Require the upstreamed Net::LDAP monkeypatch for Rex::Socket usage
in the Exploit::Remote::LDAP namespace to address some of the
problems this creates until a proper Rex::Proto::LDAP::Client is
implemented.

Testing: None, yet

lib/msf/core/exploit/remote/ldap.rb

@@ -4,7 +4,7 @@
 # This mixin is a wrapper around Net::LDAP
 #
 
-require 'net-ldap'
+require 'rex/proto/ldap'
 
 module Msf
   module Exploit::Remote::LDAP