Merge branch 'cp/unit-test-reftable-stack'

Another reftable test migrated to the unit-test framework.

* 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

diff --cc Makefile
Simple merge

diff --cc t/helper/test-tool.c
Simple merge

diff --cc t/helper/test-tool.h
Simple merge