Merge remote-tracking branch 'upstream/stable-1.8' into stable-1.9

.cirrus.yml

src/libpmemobj/heap.c

src/libpmemobj/memops.c

src/libpmemobj/tx.c

src/libpmemobj/ulog.c

src/test/obj_persist_count/out1.log.match

src/test/obj_reorder_basic/obj_reorder_basic.c

src/test/unittest/unittest.sh