Merge branch 'ps/reftable-fixes' into ps/reftable-fixes-and-optims

* ps/reftable-fixes: reftable/block: reuse buffer to compute record keys reftable/block: introduce macro to initialize `struct block_iter` reftable/merged: reuse buffer to compute record keys reftable/stack: fix use of unseeded randomness reftable/stack: fix stale lock when dying reftable/stack: reuse buffers when reloading stack reftable/stack: perform auto-compaction with transactional interface reftable/stack: verify that `reftable_stack_add()` uses auto-compaction reftable: handle interrupted writes reftable: handle interrupted reads reftable: wrap EXPECT macros in do/while