Add counters used by SNMP:
--n_err_state (state different than WR_TRACK_PHASE)
--n_err_offset (offset exceeded SNMP_MAX_OFFSET)
--n_err_delta_rtt (delta rtt exceeded SNMP_MAX_DELTA_RTT)
--n_err_rxtx_deltas (any delta_*x_* bigger than SNMP_MAX_RXTX_DELTAS)
All these counters are increased on servo update if error condition is met

Due to above, increase WRS_PPSI_SHMEM_VERSION to 6
Signed-off-by: Adam Wujek <adam.wujek@cern.ch>