Merge pull request #5011 from wlemkows/pmem2-source-get-fd-handle

doc/Makefile

doc/libpmem2/.gitignore

doc/libpmem2/pmem2_source_get_fd.3.md

doc/libpmem2/pmem2_source_get_handle.3.md

src/include/libpmem2.h

src/libpmem2/libpmem2.def

src/libpmem2/libpmem2.link.in

src/libpmem2/source_posix.c

src/libpmem2/source_windows.c

src/test/pmem2_source/TESTS.py

src/test/pmem2_source/pmem2_source.c

src/test/scope/out13.log.match

src/test/scope/out14.log.match