Fix missing explicit integer to floating-point conversion.

src/pio_dist_grid.c

@@ -1178,7 +1178,7 @@ cdiPioDistGridDefAReductions(grid_t *gridptr, size_t saIdx)
         if (saIdx == cdiPioGDsaXVals)
           {
             double xval0 = scanVals[0], xvalW = scanVals[lsize];
-            refInc = (fabs(xvalW) - fabs(xval0))/(gsize - 1);
+            refInc = (fabs(xvalW) - fabs(xval0))/(double)(gsize - 1);
           }
         else if (saIdx == cdiPioGDsaYVals)
           {