t: port reftable/readwrite_test.c to the unit testing framework

Makefile

@@ -1341,6 +1341,7 @@ UNIT_TEST_PROGRAMS += t-oidtree
 UNIT_TEST_PROGRAMS += t-prio-queue
 UNIT_TEST_PROGRAMS += t-reftable-basics
 UNIT_TEST_PROGRAMS += t-reftable-merged
+UNIT_TEST_PROGRAMS += t-reftable-readwrite
 UNIT_TEST_PROGRAMS += t-reftable-record
 UNIT_TEST_PROGRAMS += t-strbuf
 UNIT_TEST_PROGRAMS += t-strcmp-offset
@@ -2682,7 +2683,6 @@ REFTABLE_OBJS += reftable/writer.o
 REFTABLE_TEST_OBJS += reftable/block_test.o
 REFTABLE_TEST_OBJS += reftable/dump.o
 REFTABLE_TEST_OBJS += reftable/pq_test.o
-REFTABLE_TEST_OBJS += reftable/readwrite_test.o
 REFTABLE_TEST_OBJS += reftable/stack_test.o
 REFTABLE_TEST_OBJS += reftable/test_framework.o
 REFTABLE_TEST_OBJS += reftable/tree_test.o

reftable/reftable-tests.h

@@ -13,7 +13,6 @@ int basics_test_main(int argc, const char **argv);
 int block_test_main(int argc, const char **argv);
 int pq_test_main(int argc, const char **argv);
 int record_test_main(int argc, const char **argv);
-int readwrite_test_main(int argc, const char **argv);
 int stack_test_main(int argc, const char **argv);
 int tree_test_main(int argc, const char **argv);
 int reftable_dump_main(int argc, char *const *argv);

t/helper/test-reftable.c

@@ -8,7 +8,6 @@ int cmd__reftable(int argc, const char **argv)
 	block_test_main(argc, argv);
 	tree_test_main(argc, argv);
 	pq_test_main(argc, argv);
-	readwrite_test_main(argc, argv);
 	stack_test_main(argc, argv);
 	return 0;
 }