obj: fix typo in comment
libpmem.h: add missing header stdint.h

The uint64_t type requires stdint.h, for example.
Merge pull request #5 from ldorau/obj-fix-typo-in-comment

obj: fix typo in comment
Merge pull request #6 from ldorau/libpmem.h-add-missing-header-stdint.h

libpmem.h: add missing header stdint.h
obj: add pmemobj_oids_equal()
obj: simple doubly linked list