Avoid build break on non-unix environment (#12)
Avoid build break on non-unix environment (#12)

src/tape_drivers/ibm_tape.c makes a build break on MinGW. This fix avoid
this with dummy key data.
LinearTapeFileSystem/ltfs,LinearTapeFileSystem/ltfs,LinearTapeFileSystem/ltfs,LinearTapeFileSystem/ltfs,LinearTapeFileSystem/ltfs