This patch, for Bugzilla 2.16.2, allows it to use the perl-ldap (Net::LDAP) library, instead of Mozilla::LDAP::Conn, which I seem to have enormous trouble compiling.
The current version is bugzilla-perl-ldap-2.16.4-0.1-patch. Thanks to Felix (no surname supplied) for updating this.
bugzilla-perl-ldap-2.16.2-0.2-patch. Note that there was a security bug in the 2.16.1-0.1 patch which allowed unauthenticated logins. Thanks to Trevor Nuridin for pointing that out.