Update to 1.868
    
    - New upstream release 1.868
      - Bug fix for UTF-8 issues during inter-process communication:
        - This update required undoing optimizations specific to scalar args
        - Essentially, IPC involves serialization for everything going forward
        - Install Sereal::Encoder and Sereal::Decoder for better performance in
          Perl 5.8.8+
      - MCE options flush_stdout, flush_stderr, and flush_file now default to
        enabled for the MCE->print, MCE->printf, and MCE->say output routines
      - Improved MCE::Child with threads-like detach capability (see POD)
      - Improved IPC in MCE::Queue with permanent fast-like dequeue including
        dequeue_nb; going forward, the fast and barrier options are silently
        ignored if specified (i.e. no-op)
      - Improved IPC performance on Linux
      - Completed threads-like detach capability in MCE::Child
      - Resolved MCE::Channel failing when calling dequeue multiple times on an
        ended channel
      - MCE->say, MCE->print, and MCE->printf now return 1