xbps_repo_open: fix f7b4587 and really pass the correct size this time.

lib/repo.c

@@ -78,7 +78,7 @@ repo_get_dict(struct xbps_repo *repo)
 		if (adata == NULL) {
 			adata = malloc(size);
 		} else {
-			adata = realloc(adata, size * offset);
+			adata = realloc(adata, size+offset);
 			if (adata == NULL) {
 				free(adata);
 				return NULL;