Rollup merge of #22157 - tbu-:pr_debug_collections, r=alexcrichton

 r? @Gankro

diff --cc src/libcollections/bit.rs
Simple merge

diff --cc src/libcollections/btree/map.rs
Simple merge

diff --cc src/libcollections/btree/set.rs
Simple merge

diff --cc src/libcollections/enum_set.rs
Simple merge

diff --cc src/libcollections/linked_list.rs
Simple merge

diff --cc src/libcollections/vec_deque.rs
Simple merge

diff --cc src/libcollections/vec_map.rs
Simple merge