fix(sysdeps): handle empty Linux packages

[mistydemeo]

We've seen a minor UI issue with Linux dependencies. I anticipated catching the error status output from dpkg -S and reacting to that, but we were still getting cases where not finding the package and accidentally returning an empty string as the "package". This checks for that case and properly handles it.

Before this fix, the linkage reporter was giving us outputs like:

/path/to/lib ()

And with this fix, it looks like:

/path/to/lib

[mistydemeo]

Confirmed this works.

╞════════════════════╪════════════════════════════════════════════════════════════════════════════════╡
│ System             ┆ /usr/lib/aarch64-linux-gnu/libgtk-3.so.0.2404.29 (libgtk-3-0)                  │
│                    ┆ /usr/lib/aarch64-linux-gnu/libgobject-2.0.so.0.7200.4 (libglib2.0-0)           │
│                    ┆ /usr/lib/aarch64-linux-gnu/libstdc++.so.6.0.30 (libstdc++6)                    │
│                    ┆ /usr/lib/aarch64-linux-gnu/libgcc_s.so.1                                       │