Build on HP-UX fixed

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
Fix bug of removing pipe with the current priority

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>
Implemented `accept_errors` counter for tcp
Add error counters in ipc transport
Implemented message and bytes counters
Implement `current_connections` counter
Implement dropped and broken connections
Implement `current_std_priority` counter
Merge branch 'master' of github.com:250bpm/nanomsg into monitoring_internals
Finished implementation of current_snd_priority
Implement statistics timer
Socket statistics printed to the stderr