MueLu: fixing the count of aggregated nodes in refactored Phase2a of …

…aggregation, see #6325

A piece of logic is wrong in the algorithms that counts
how many nodes have been aggregated in Phase2a of aggregation.
This commit fixes that by individually counting every node
that is being aggregated instead of counting all the nodes in
a newly formed aggregate, at once.

packages/muelu/src/Graph/UncoupledAggregation/MueLu_AggregationPhase2aAlgorithm_kokkos_def.hpp

@@ -165,13 +165,13 @@ namespace MueLu {
                                         if(graph.isLocalNeighborVertex(neigh) &&
                                            aggStat(neigh) == READY &&
                                            aggSize < maxNodesPerAggregate) {
-                                          aggStat(neigh)   = AGGREGATED;
+                                          aggStat(neigh)         = AGGREGATED;
                                           vertex2AggId(neigh, 0) = aggIndex;
                                           procWinner(neigh, 0)   = myRank;
+                                          lNumNonAggregatedNodes = lNumNonAggregatedNodes - 1;
                                         }
                                       }
                                     }
-                                    lNumNonAggregatedNodes -= aggSize;
                                   }
                                 }
                               }, tmpNumNonAggregatedNodes);