Creates files even if CRC fails

```bash
$ file zero1MiB.bin
zero1MiB.bin: cannot open `zero1MiB.bin' (No such file or directory)
$ ../safe_unzip /tmp/x/zero.corrupted.zip --validate-first -v
[1/1] zero1MiB.bin
Error: I/O error: Invalid checksum
$ file zero1MiB.bin
zero1MiB.bin: data
$
```
