message: wallet: Use GetSelectionAmount for target value calculations
  For target value calculations, GetSelectionAmount should be used, not
  m_effective_value or m_value.
  Specifically, ApproximateBestSubset mistakenly uses m_value when
  calculating whether the target value has been met. This has been changed
  to use GetSelectionAmount.
diff: @@ -195,7 +195,7 @@ static void ApproximateBestSubset(const std::vector<OutputGroup>& groups, const
  //the selection random.
  if (nPass == 0 ? insecure_rand.randbool() : !vfIncluded[i])
  {
  - nTotal += groups[i].m_value;
  + nTotal += groups[i].GetSelectionAmount();
  vfIncluded[i] = true;
  if (nTotal >= nTargetValue)
  {
  @@ -205,7 +205,7 @@ static void ApproximateBestSubset(const std::vector<OutputGroup>& groups, const
  nBest = nTotal;
  vfBest = vfIncluded;
  }
  - nTotal -= groups[i].m_value;
  + nTotal -= groups[i].GetSelectionAmount();
  vfIncluded[i] = false;
  }
  }
  