Use size_t/ssize_t for nValue-related variables

Meter.c

@@ -300,7 +300,7 @@ static void GraphMeterMode_draw(Meter* this, int x, int y, int w) {
       memmove(data->values + (data->nValues - oldNValues), data->values, oldNValues * sizeof(*data->values));
       memset(data->values, 0, (data->nValues - oldNValues) * sizeof(*data->values));
    }
-   const int nValues = data->nValues;
+   const size_t nValues = data->nValues;
 
    const char* const* GraphMeterMode_dots;
    int GraphMeterMode_pixPerRow;
@@ -327,18 +327,20 @@ static void GraphMeterMode_draw(Meter* this, int x, int y, int w) {
       struct timeval delay = { .tv_sec = globalDelay / 10, .tv_usec = (globalDelay % 10) * 100000L };
       timeradd(&host->realtime, &delay, &(data->time));
 
-      for (int i = 0; i < nValues - 1; i++)
+      for (size_t i = 0; i < nValues - 1; i++)
          data->values[i] = data->values[i + 1];
 
       data->values[nValues - 1] = sumPositiveValues(this->values, this->curItems);
    }
 
-   int i = nValues - (w * 2), k = 0;
+   assert(nValues <= SSIZE_MAX);
+   ssize_t i = (ssize_t)nValues - (w * 2);
+   ssize_t k = 0;
    if (i < 0) {
       k = -i / 2;
       i = 0;
    }
-   for (; i < nValues - 1; i += 2, k++) {
+   for (; i < (ssize_t)nValues - 1; i += 2, k++) {
       int pix = GraphMeterMode_pixPerRow * GRAPH_HEIGHT;
       if (this->total < 1)
          this->total = 1;