Ceph

in jewel, we already have new LDAPHelper constructor

so, we should cherry-pick following commit to make test pass:
8328daa81a823dc42dd730c6e744a83231d30843

[ 71%] Building CXX object src/test/CMakeFiles/test_rgw_ldap.dir/test_rgw_ldap.cc.o
/root/github/vicente/ceph/src/test/test_rgw_ldap.cc:51:20: error: no matching function for call to ‘rgw::LDAPHelper::LDAPHelper(std::string&, std::string&, std::string&, std::string&, std::string&)’
         ldap_dnattr);
                    ^
/root/github/vicente/ceph/src/test/test_rgw_ldap.cc:51:20: note: candidate is:
In file included from /root/github/vicente/ceph/src/test/test_rgw_ldap.cc:22:0:
/root/github/vicente/ceph/src/rgw/rgw_ldap.h:40:5: note: rgw::LDAPHelper::LDAPHelper(std::string, std::string, std::string, std::string, std::string, std::string)
     LDAPHelper(std::string _uri, std::string _binddn, std::string _bindpw,
     ^
/root/github/vicente/ceph/src/rgw/rgw_ldap.h:40:5: note:   candidate expects 6 arguments, 5 provided
make[2]: *** [src/test/CMakeFiles/test_rgw_ldap.dir/test_rgw_ldap.cc.o] Error 1
make[1]: *** [src/test/CMakeFiles/test_rgw_ldap.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....