I supplied meta.outputsToInstall automatically in all
mkDerivation products, but some packages still don't use it.
The reported case: jekyll -> bundlerEnv -> buildEnv -> runCommand.
- Now `pkg.outputUnspecified = true` but this attribute is missing in
every output, so we can recognize whether the user chose or not.
If (s)he didn't choose, we put `pkg.bin or pkg.out or pkg` into
`systemPackages`.
- `outputsToLink` is replaced by `extraOutputsToLink`.
We add extra outputs *regardless* of whether the user chose anything.
It's mainly meant for outputs with docs and debug symbols.
- Note that as a result, some libraries will disappear from system path.
Originally wanted to include ignoreCollisions in cups-progs, but I think
it's better if we use ignoreCollisions only if there are _real_
collisions between files with different contents.
Of course, we also check whether the file permissions match, so you get
a collision if contents are the same but the permissions are different.
Signed-off-by: aszlig <aszlig@redmoonstudios.org>
