Merge branch 'ps/reftable-styles'

Code clean-up in various reftable code paths.

* ps/reftable-styles:
  reftable/record: improve semantics when initializing records
  reftable/merged: refactor initialization of iterators
  reftable/merged: refactor seeking of records
  reftable/stack: use `size_t` to track stack length
  reftable/stack: use `size_t` to track stack slices during compaction
  reftable/stack: index segments with `size_t`
  reftable/stack: fix parameter validation when compacting range
  reftable: introduce macros to allocate arrays
  reftable: introduce macros to grow arrays

diff --cc reftable/merged_test.c
Simple merge

diff --cc reftable/reader.c
Simple merge

diff --cc reftable/readwrite_test.c
Simple merge

diff --cc reftable/stack.c
Simple merge

diff --cc reftable/stack_test.c
Simple merge

diff --cc reftable/writer.c
index e23953e498a86b3dd6d6665853354a9cf3dcde2a,47b344813264e7bcb4c2e793d4a1d795e2912a4a..1d9ff0fbfabcc387e29697c0458467c882708c39
--- 1/reftable/writer.c
--- 2/reftable/writer.c
+++ b/reftable/writer.c
@@@ -121,11 -121,9 +121,10 @@@ static struct strbuf reftable_empty_str
  
  struct reftable_writer *
  reftable_new_writer(ssize_t (*writer_func)(void *, const void *, size_t),
 +                  int (*flush_func)(void *),
                    void *writer_arg, struct reftable_write_options *opts)
  {
-       struct reftable_writer *wp =
-               reftable_calloc(sizeof(struct reftable_writer));
+       struct reftable_writer *wp = reftable_calloc(1, sizeof(*wp));
        strbuf_init(&wp->block_writer_data.last_key, 0);
        options_set_defaults(opts);
        if (opts->block_size >= (1 << 24)) {