Annotate intentional fall-through.

src/pio_dist_grid.c

@@ -456,7 +456,7 @@ cdiPioDistGridInit(grid_t *gridptr, int gridtype, int size, int xsize, int ysize
     case GRID_UNSTRUCTURED:
       for (size_t saIdx = 0; saIdx < cdiPioGDsaNum; ++saIdx) sub_arrays[saIdx].rect[0].size = size;
       irregular = true;
-      /* intended fall-through */
+      /*-fallthrough*/
     case GRID_GENERIC:
     case GRID_GAUSSIAN:
     case GRID_LONLAT: