Fix two memory leaks in crossbeam-skiplist#673

Merged

bors[bot] merged 2 commits intocrossbeam-rs:masterfrom sticnarf:skiplist-leak

Mar 4, 2021

+21-4

Commits on Mar 4, 2021

skiplist: decrement ref counts of nodes while iterating a range
sticnarf
committed
skiplist: always return the entry after acquire succeeds in remove
sticnarf
committed