[sharutils] find_archive() passes off_t to fseek()

Hello,

current (4.14) src/unshar.c:find_archive() has third argument of type off_t,
and passed the value to fseek(3) function which expects long. Standard library
offers fseeko(3) for this reason.

I propose replace fseek() call with fseeko().

-- Petr

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v2.0.22 (GNU/Linux)

iF4EABEIAAYFAlKcNkUACgkQEsnFx2fG+qJ95QEAn9ZlznNAbzaZ+8UeccrkrZgc
UScedsnPX84ws2D3UUUBAJ1XrBNTD56W+mP9bDv8K3X7PKYmeCDJxRLiK3E8JD4y
=P6oi
-----END PGP SIGNATURE-----