Revert "Removed unused grid_t member extraData."

* extraData will be used after all.

src/cdf_lazy_grid.c

@@ -32,6 +32,7 @@ static bool cdfLazyInitialized;
 
 void cdfLazyGridDestroy(struct cdfLazyGrid *lazyGrid)
 {
+  lazyGrid->base.extraData = NULL;
   if (lazyGrid->base.area == cdfPendingLoad)  lazyGrid->base.area = NULL;
   if (lazyGrid->base.x.vals == cdfPendingLoad) lazyGrid->base.x.vals = NULL;
   if (lazyGrid->base.y.vals == cdfPendingLoad) lazyGrid->base.y.vals = NULL;

src/grid.c

@@ -191,6 +191,7 @@ void grid_init(grid_t *gridptr)
                96  = 128 * 0                + 64 *        1         + 32 * 1
      Default / implicit scanning mode is 64:
                         i and j scan positively, i points are consecutive (row-major)        */
+  gridptr->extraData     = NULL;
 }
 
 

src/grid.h

@@ -139,6 +139,7 @@ struct grid_t {
   struct gridaxis_t x;
   struct gridaxis_t y;
   const struct gridVirtTable *vtable;
+  void   *extraData;
   cdi_atts_t atts;
   int  scanningMode;
   bool iScansNegatively, jScansPositively, jPointsAreConsecutive;