Check backend I/F is suitable with the LTFS 3rd party backend project (#119)
Check backend I/F is suitable with the LTFS 3rd party backend project (#119)

* Confirm 3rd party backend is buidable or not
* Check 3rd party backend with --enable-checkonly

LinearTapeFileSystem/ltfs,LinearTapeFileSystem/ltfs,LinearTapeFileSystem/ltfs,LinearTapeFileSystem/ltfs,LinearTapeFileSystem/ltfs