* void *tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), AVTreeNode **next){
* if(!*next) *next= av_mallocz(av_tree_node_size);
* return av_tree_insert(rootp, key, cmp, next);
* void *tree_insert(struct AVTreeNode **rootp, void *key, int (*cmp)(void *key, const void *b), AVTreeNode **next){
* if(!*next) *next= av_mallocz(av_tree_node_size);
* return av_tree_insert(rootp, key, cmp, next);