fix(rowgroup): RGData now uses uint64_t counter for the fixed sizes columns data buf.

The buffer can utilize > 4GB RAM that is necessary for PM side join.
	RGData ctor uses uint32_t allocating data buffer.
 	This fact causes implicit heap overflow.

dbcon/joblist/tuplehashjoin.cpp

@@ -417,6 +417,7 @@ void TupleHashJoinStep::smallRunnerFcn(uint32_t index, uint threadID, uint64_t*
   smallRG.initRow(&r);
   try
   {
+    // Very unfortunate choice for the type b/c of RM::getMemory type.
     ssize_t rgSize;
     bool gotMem;
     goto next;