Switch to FifoMessenger in pkg_libchk.sh
Switch to FifoMessenger in pkg_libchk.sh

changed src/pkg_libchk.sh
- Only keep a single messenger instance instead of a separate listener,
  sender
- No more need to poll and sleep, reading from the FIFO is a blocking
  operation

lonkamikaze/bsda2,lonkamikaze/bsda2