* cp/unit-test-reftable-stack:
t-reftable-stack: add test for stack iterators
t-reftable-stack: add test for non-default compaction factor
t-reftable-stack: use reftable_ref_record_equal() to compare ref records
t-reftable-stack: use Git's tempfile API instead of mkstemp()
t: harmonize t-reftable-stack.c with coding guidelines
t: move reftable/stack_test.c to the unit testing framework