Changes to get fuzz targets building again after img_info cache membe…

…r changes

ossfuzz/mem_img.h

@@ -26,6 +26,7 @@ typedef struct {
   TSK_IMG_INFO img_info;
   const uint8_t *data;
   size_t size;
+  LegacyCache *cache;
 } IMG_MEM_INFO;
 
 static ssize_t mem_read(TSK_IMG_INFO *img_info, TSK_OFF_T offset, char *buf,
@@ -49,10 +50,7 @@ static ssize_t mem_read(TSK_IMG_INFO *img_info, TSK_OFF_T offset, char *buf,
 static void mem_close(TSK_IMG_INFO *img_info) {
   IMG_MEM_INFO *mem_info = reinterpret_cast<IMG_MEM_INFO *>(img_info);
 
-  auto cache = static_cast<LegacyCache*>(img_info->cache_holder);
-  delete cache;
-  img_info->cache_holder = nullptr;
-
+  delete mem_info->cache;
   free(mem_info);
 }
 
@@ -72,11 +70,13 @@ TSK_IMG_INFO *mem_open(const uint8_t *data, size_t size) {
   img->imgstat = mem_imgstat;
   img->size = size;
   img->sector_size = 512;
+
   inmemory_img->data = data;
   inmemory_img->size = size;
+  inmemory_img->cache = new LegacyCache();
 
   // tsk_img_cache_setup(img, 0, 0);
-  img->cache_holder = new LegacyCache();
+  img->cache_holder = inmemory_img->cache;
   img->cache_read = tsk_img_read_legacy;
 
   return img;