As mentioned in https://github.com/ros/rosdistro/pull/3430#issue-29089535 above:
`libomniorb4-dev` depends directly or indirectly on `libomniorb4-1`, `libomnithread3-dev` and `libomnithread3c2`. Most other rosdep keys also only contain the `-dev` package and not the corresponding library or other development packages they depend on.

I did not verify these dependencies for the older Ubuntu releases before oneiric and therefore did not change those.

For precise:
```
Package: libomniorb4-dev
Depends: libomniorb4-1 (= 4.1.6-1), libomnithread3-dev (= 4.1.6-1), libssl-dev, pkg-config

Package: libomniorb4-1
Depends: libc6 (>= 2.4), libgcc1 (>= 1:4.1.1), libomnithread3c2 (>= 4.0.6), libssl1.0.0 (>= 1.0.0), libstdc++6 (>= 4.1.1)

Package: libomnithread3-dev
Depends: libomnithread3c2 (= 4.1.6-1), pkg-config
```

See also http://packages.ubuntu.com/libomniorb4-dev.