smb_fseek return value will be cut on 32bit os

[solidusex]

ssize_t smb_fseek(smb_session *s, smb_fd fd, off_t offset, int whence);

ssize_t in the 32bit os is 4 bytes, return value on larger than 4g file will be cut off, so please change to int64_t, thank you.