reftable/writer: drop Git-specific QSORT() macro

The reftable writer accidentally uses the Git-specific `QSORT()` macro.
This macro removes the need for the caller to provide the element size,
but other than that it's mostly equivalent to `qsort()`.

Replace the macro accordingly to make the library usable outside of Git.

Signed-off-by: Patrick Steinhardt <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pks-t

reftable/writer.c

@@ -399,7 +399,8 @@ int reftable_writer_add_refs(struct reftable_writer *w,
 {
 	int err = 0;
 
-	QSORT(refs, n, reftable_ref_record_compare_name);
+	if (n)
+		qsort(refs, n, sizeof(*refs), reftable_ref_record_compare_name);
 
 	for (size_t i = 0; err == 0 && i < n; i++)
 		err = reftable_writer_add_ref(w, &refs[i]);
@@ -491,7 +492,8 @@ int reftable_writer_add_logs(struct reftable_writer *w,
 {
 	int err = 0;
 
-	QSORT(logs, n, reftable_log_record_compare_key);
+	if (n)
+		qsort(logs, n, sizeof(*logs), reftable_log_record_compare_key);
 
 	for (size_t i = 0; err == 0 && i < n; i++)
 		err = reftable_writer_add_log(w, &logs[i]);