Set free'd pointers to NULL whenever they are not reassigned immediat…

…ely after

cJSON.c

@@ -235,10 +235,12 @@ CJSON_PUBLIC(void) cJSON_Delete(cJSON *item)
         if (!(item->type & cJSON_IsReference) && (item->valuestring != NULL))
         {
             global_hooks.deallocate(item->valuestring);
+            item->valuestring = NULL;
         }
         if (!(item->type & cJSON_StringIsConst) && (item->string != NULL))
         {
             global_hooks.deallocate(item->string);
+            item->string = NULL;
         }
         global_hooks.deallocate(item);
         item = next;
@@ -820,6 +822,7 @@ static cJSON_bool parse_string(cJSON * const item, parse_buffer * const input_bu
     if (output != NULL)
     {
         input_buffer->hooks.deallocate(output);
+        output = NULL;
     }
 
     if (input_pointer != NULL)
@@ -1165,6 +1168,7 @@ static unsigned char *print(const cJSON * const item, cJSON_bool format, const i
 
         /* free the buffer */
         hooks->deallocate(buffer->buffer);
+        buffer->buffer = NULL;
     }
 
     return printed;
@@ -1173,11 +1177,13 @@ static unsigned char *print(const cJSON * const item, cJSON_bool format, const i
     if (buffer->buffer != NULL)
     {
         hooks->deallocate(buffer->buffer);
+        buffer->buffer = NULL;
     }
 
     if (printed != NULL)
     {
         hooks->deallocate(printed);
+        printed = NULL;
     }
 
     return NULL;
@@ -1218,6 +1224,7 @@ CJSON_PUBLIC(char *) cJSON_PrintBuffered(const cJSON *item, int prebuffer, cJSON
     if (!print_value(item, &p))
     {
         global_hooks.deallocate(p.buffer);
+        p.buffer = NULL;
         return NULL;
     }
 
@@ -2987,4 +2994,5 @@ CJSON_PUBLIC(void *) cJSON_malloc(size_t size)
 CJSON_PUBLIC(void) cJSON_free(void *object)
 {
     global_hooks.deallocate(object);
+    object = NULL;
 }