Revision 32953

   Changes to handle the Unix sock length problem on MacOsX.
   In XrdProofdManager:
    - add support for a new directive 'xpd.sockpathdir' to control the location under which
      the unix sockets for the sessions are created; default is <admin_path>/.xproofd.<xproofd_port>/socks .
    - add getter XrdProofdManager::SockPathDir() .
   In XrdProofdProofServMgr:
    - create the unix sockets under XrdProofdManager::SockPathDir()
    - compactify the name of the unix socket: xpd.<daemon_pid>.<proofserv_pid>
    - add a warning if the global path is longer that 100 chars.