refactor to allow multiple hooks for one type

include/list.h

@@ -0,0 +1,20 @@
+#ifndef UC_LLIST_H
+#define UC_LLIST_H
+
+#include <stdbool.h>
+
+struct list_item {
+    struct list_item *next;
+    void *data;
+};
+
+struct list {
+    struct list_item *head, *tail;
+};
+
+struct list *list_new(void);
+void list_clear(struct list *list);
+void *list_append(struct list *list, void *data);
+bool list_remove(struct list *list, void *data);
+
+#endif