Hi,

I noticed a bit confusing message when using `--package` with
`dpkg-shlibdeps`.

```
$ dpkg-shlibdeps --package foo
dpkg-shlibdeps: error: unknown option '--package'

Use --help for program usage information.
```

However, the man page list `--package=foo` and that variant works. In
other words, the option *is* known.

I am unsure whether the bug is that `--package foo` should be accepted,
or that the error message should say that `=foo` is required. But status
quo definitely seems to be undesired either way.

Best regards,
Niels