fix: invalid file seek position.

In windows, line head position does not equal previous_line head + previous_line bytesize.
But this does not occur in the file containing only LF, this occur in the file containing CR/LF.
fix ambiguous initialization for previous_seek.
Rollback previous changes.
Suppress automatically conversion EOL <-> CRLF.
Merge pull request #319 from toruuetani/spike-windows-tail-invalid-seek

Fix invalid file seek in the file containing CRLF