Add N2N_UPLINK_HOST and N2N_UPLINK_PORT env variables which point to a redirector higher
              up in the hierarchy to which requests are redirected in case the file is
              not found in EOS. Both of them need to be set in /etc/sysconfig/xrootd

XrdCmsClient: Modify the Locate method so that it returns the address of the redirector
              up in the hierarchy when LFC says that the file is not in EOS

XrdOfs: Modify the stat function so that it returns SFS_ERROR when the file is not in EOS
              according to the result of the XrdCmsClient::Locate call

RPM: Call ldconfig in both the post install and post uninstall phase