Fix: Resource leak

[Youw]

Windows: hidapi_descriptor_reconstruct.c:

CID 1530054 (2): Wrong sizeof argument (SIZEOF_MISMATCH) [[select issue](https://scan5.scan.coverity.com/defectInstanceId=53225971&fileInstanceId=239845965&mergedDefectId=1530054)]
   	278. alloc_fn: Storage is returned from allocation function malloc.
   	279. var_assign: Assigning: main_item_list = storage returned from malloc(8ULL).
381        struct rd_main_item_node *main_item_list = (struct rd_main_item_node*)malloc(sizeof(main_item_list));
   	
CID 1530055 (#1 of 1): Resource leak (RESOURCE_LEAK)
280. overwrite_var: Overwriting main_item_list in main_item_list = NULL leaks the storage that main_item_list points to.
382        main_item_list = NULL; // List root

Very strange that ASAN didn't catch it.
CC: @JoergAtGithub