message: Fix -Wsign-compare warnings in Qt tx graph widget
diff: @@ -293,8 +293,8 @@ void TransactionGraphWidget::setTransactionsPerSecond(double nTxPerSec,
  updateTransactionsPerSecondLabelValues();
  // Limit redraw requests
  - static int64_t nLastRedrawTime = GetTimeMillis();
  - int64_t nCurrentTime = GetTimeMillis();
  + static uint64_t nLastRedrawTime = (uint64_t)GetTimeMillis();
  + uint64_t nCurrentTime = (uint64_t)GetTimeMillis();
  if (nCurrentTime >= nLastRedrawTime + nRedrawRateMillis)
  {
  update();
  @@ -313,7 +313,7 @@ void TransactionGraphWidget::updateTransactionsPerSecondLabelValues()
  size_t countAll = vSmoothedSamples.size();
  size_t countDisplay = countAll < numSamples ? countAll : numSamples;
  float tMaxSamples = 0.0f, tMaxDisplay = 0.0f;
  - for (int i = 0; i < vInstantaneousSamples.size(); i++)
  + for (size_t i = 0; i < (size_t)vInstantaneousSamples.size(); i++)
  {
  float f = vInstantaneousSamples.at(i);
  tSumAll += f;
  @@ -348,7 +348,7 @@ void TransactionGraphWidget::updateTransactionsPerSecondLabelValues()
  tSumDisplay = 0.0f;
  tMaxSamples = 0.0f;
  tMaxDisplay = 0.0f;
  - for (int i = 0; i < vSmoothedSamples.size(); i++)
  + for (size_t i = 0; i < (size_t)vSmoothedSamples.size(); i++)
  {
  float f = vSmoothedSamples.at(i);
  tSumAll += f;
  