Fixed latency measurements.

The typical log line is:
[eric@localhost CTA (master)]$ tail -1 /var/tmp/cta-rados-locking.log
Tue Jun  5 17:21:17 2018 totalCalls=9 averageAttempts=1 waitCount=0 minAttempts=1 maxAttempts=1 averageTotalTime=0.00149167 minTotalTime=0.001088 maxTotalTime=0.001986 averageLatency=0.00149167 minLatency=0.001088 maxLatency=0.001986 averageLatencyMultiplier=0 minLatencyMultiplier=0 maxLatencyMultiplier=0 samplingTime=21.3298