HPCC-15933 Add a new NumCompares stat ready for generating in 6.2

Signed-off-by: Gavin Halliday <gavin.halliday@lexisnexis.com>

system/jlib/jstatcodes.h

@@ -177,6 +177,7 @@ enum StatisticKind
     StNumExecutions,
     StTimeTotalNested,
     StCycleLocalExecuteCycles,
+    StNumCompares,
 
     StMax,
 

system/jlib/jstats.cpp

@@ -586,6 +586,7 @@ static const StatisticMeta statsMetaData[StMax] = {
     { NUMSTAT(Executions) },
     { TIMESTAT(TotalNested) },
     { CYCLESTAT(LocalExecuteCycles) },
+    { NUMSTAT(Compares) },
 };