declare gridHandle as void* if grib_api is not available

src/gribapi_utilities.c

+static int dummy;
+
 #ifdef HAVE_LIBGRIB_API
 
 #include "gribapi_utilities.h"

src/iterator_grib.c

-#ifdef HAVE_LIBGRIB_API
-
 #include "iterator_grib.h"
 
 #include "cdi_int.h"
@@ -17,6 +15,8 @@
 #include <string.h>
 
 
+#ifdef HAVE_LIBGRIB_API
+
 //Since the error handling in constructors is usually very closely related to the workings of a destructor,
 //this function combines both functions in one, using a centralized exit.
 //The mode of operation depends on whether me is a NULL pointer on entry:
@@ -127,6 +127,7 @@ char* cdiGribIterator_serialize(CdiIterator* super)
   free(escapedPath);
   return result;
 }
+#endif
 
 CdiGribIterator* cdiGribIterator_deserialize(const char* description)
 {
@@ -170,6 +171,7 @@ fail:
   return NULL;
 }
 
+#ifdef HAVE_LIBGRIB_API
 static void cdiGribIterator_ensureBuffer(CdiGribIterator* me, size_t requiredSize)
 {
   if(me->bufferSize < requiredSize)

src/iterator_grib.h

@@ -24,6 +24,8 @@ typedef struct CdiGribIterator {
   size_t bufferSize, curRecordSize;
 #ifdef HAVE_LIBGRIB_API
   grib_handle* gribHandle;
+#else
+  void* gribHandle;
 #endif
 } CdiGribIterator;