Merge pull request #3960 from pbalcer/obj-ulog-redo

src/libpmemobj/memops.c

src/libpmemobj/memops.h

src/libpmemobj/tx.c

src/test/obj_memops/obj_memops.c

src/test/obj_ulog_size/TESTS.py

src/test/obj_ulog_size/obj_ulog_size.c

src/test/obj_ulog_size/out0.log.match

src/test/obj_ulog_size/out1.log.match

src/test/obj_ulog_size/out2.log.match